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THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 


LOGIN  BROS. 

MEDICAL  BOOKS 
1814  W.  HARRISON  ST.  CHICAC 


Visual  Economics, 


WITH    RULES   FOR 


ESTIMATION    OF   THE    EARNING 

ABILITY  AFTER   INJURIES 

TO  THE  EYES. 


BY 


H.  MAGNUS,  Med.  Dr.,  of  Breslau,  Germany, 

(Professor  of  Ophthalmology  in  the  University 
of  Breslau,  etc.,  etc.,) 

AND 

H.  V.  WURDEMANN,  M.  D.,  of  Milwaukee,  Wis., 

U.  S.  A., 

(Professor  of  Ophthalmology  to  the  Milwaukee 
Medical  College,  etc.,  etc.) 


FOR  THE  USE  OF  THE  MEDICAL 
AND  LEGAL  PROFESSIONS, 
BUSINESS  CORPORATIONS  AND 
INSURANCE    OFFICIALS 


Published  by 

C.  FORTH,  105  Grand  Avenue,  Milwaukee,  Wis.,  U.  S.  A. 

1902. 


copyr;ighted,  i  902, 

by 
C.    PO  RTH, 


Milwaukee,   Wisconsin. 


DEDICATED 

to  the 

HON.    JOSEPH    V.    QUARLES, 

Senator  of  the  United  States  of  America 
and  Member  of  the  Wisconsin  Bar. 


PLATE  L 


FOR  TRANSPOSITION  OF  THE  SCIENTIFIC  STANDARD  OF  VISUAL 
ACUITY  INTO  ECONOMIC   TERMS. 


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The  coarse  full  line  (I)  denotes  the  course  or  curve  of  the  Visual 
Acuity  according  to  the  Scientific  Standard, 

The  fine  full  line  (II)  is  the  Economic  valuation  for  vocations  having 
higher  visual  demands,  and  the  broken  line  (III)  the  Economic  valuation 
for  lower  demands. 


(See  text  Chapter  VI.,  §  12,  and  Chapter  VIII.,  §  17.) 


D 


PREFACE. 


HE  great  interest  and  large  circulation  with  which  the  original 
edition  of  Magnus'  work,  "Leitfaden  fiir  Begutachtung  und 
Berechnung  von  Unfallsbeschadigungen  der  Augen,"  was  re- 
ceived after  its  publication  in  1894,  the  legal  standing  which 
this  and  the  second  edition  of  1897  has  achieved  in  Germany,  the 
fascination  which  the  reading  of  the  original  work  had  for  the  American 
author,  and  the  practical  use  which  he  has  made  of  the  formulas  and 
maxims  of  Magnus,  led  him,  in  May,  1900,  to  request  the  permission 
of  Prof.  Magnus  to  allow  of  a  translation,  adapted  to  the  legal,  medical 
and  economic  requirements  of  America,  to  be  published  in  this  country, 
which  was  cheerfully  given  May  11th.  The  American  editor  at  first 
made  a  literal  translation  of  the  work,  but  owing  to  the  virgin  field,  as 
yet  untouched  in  English  medical  literature,  and  almost  unthought  of  in 
insurance  circles,  and  the  special  demands  of  American  law,  it  was 
believed  that  a  simple  translation  would  not  meet  the  requirements  of 
American  and  English  readers.  Therefore,  with  the  consent  and  aid  of 
Prof.  Magnus,  the  work  has  been  entirely  re-written  by  the  American 
author.  The  introduction  and  all  of  Chapters  1,  XIX  and  Part  111  are 
new.  A  large  part  of  Chapter  VI,  i.  e.,  that  more  particularly  relating 
to  American  railway  employees,  and  interpolations  in  many  places 
throughout  the  text  are  new.  The  formulas  and  calculations  are  adapted 
from  those  in  Magnus'  second  edition.  We  are  greatly  indebted  to 
Dr.  Howard  F.  Hansell.  of  Philadelphia,  for  hints  and  extracts  from 
his  paper,  "Estimation  of  the  Amount  of  Injury  to  the  Earning  Capacity 
of  the  Individual  from  Partial  or  Complete  Loss  of  Vision";  likewise 
to  Dr.  Frank  Allport.  of  Chicago,  for  information  relating  to  classes 
of  railway  employees,  and  to  Senator  Joseph  V.  Quarles,  of  Wisconsin, 
for  assistance  upon  the  forensic  portion  of  the  work. 

The  reason  for  the  publication  of  Magnus'  original  essays  was  the 
passing  of  a  Benefit  and  Accident  Insurance  Law  in  1884,  in  Germany, 
which  placed  upon  the  already  overburdened  shoulders  of  the  physician 
entirely  new  and  difficult  problems.  The  estimation  of  the  damage 
from  eye  injuries  and  indemnity  to  be  allowed  therefrom  had  heretofore 
only  been  made  from  a  philanthropic  standpoint.  Zehender  was  the 
first  to  try  to  give  a  mathematical  expression  to  such  estimations,  fol- 


lowed  later  by  Magnus,  Groenouw  and  others.  Magnus'  calculations 
are  the  only  ones  that  are  founded  upon  anatomical  and  mathematical 
data.  He  called  to  his  aid  an  expert  mathematician,  Dr.  Hugo  Rohr, 
who  gave  valuable  assistance  in  the  compilation  of  the  tables.  Magnus' 
methods,  which  have  been  adapted  to  the  use  of  American  and  English- 
speaking  peoples  in  this  edition,  may  be  carried  out  in  actual  practice, 
so  that  a  method  for  estimation  of  the  damage  to  any  workingman's 
capacity  from  ocular  injuries  and  the  indemnification  to  be  given  there- 
for, may  be  figured  in  a  manner  just  to  the  workman,  the  person  respon- 
sible for  the  damage,  to  his  employer  or  to  the  casualty  company.  We 
hope  that  this  work  will  not  only  prove  acceptable  to  the  medical  pro- 
fession of  America  and  Great  Britain,  but  also  be  received  with  interest 
by  that  of  the  law,  by  insurance  companies  and  by  corporations  which 
are  responsible  for  pecuniary  indemnification  in  the  case  of  accidents  to. 

the  eyes. 

H.   MAGNUS, 

Breslau. 

H.  V.  WURDEMANN. 
Milwaukee. 
Jan.  1,  1902. 


CONTENTS. 

Frontispiece.    Plate  I,    For  Transposition  of  the  Scientific  Standard  of 
Visual  Acuity  into  Economic  Terms.    Preface  pages  I  and  2. 


PART  FIRST. 

Introduction'.  Legal  Status  of  the  Physician  in  Relation  to  Accident 
Insurance  and  Indemnity  for  Accidents. — Different  Methods  for 
Estimation  of  the  Loss  of  Earning  Ability  from  Ocular  Accidents. 
General  Principles  for  Estimation  of  the  Relaton  of  Ocular  Injures 
to  the  Earning  Ability. — Conception  of  the  Earning  Ability  and  of 
Injuries  Thereto. — Estimation  of  the  Damage  to  Economic  Vision. 
Method  of  Mathematical  Calculation 9 

Introductiox.  Full  Earning  Ability  Synonymous  with  Visual  Earnin3 
Ability. — ^Standard  Established  by.  this  Work  for  Scientific  Esti- 
mation  11-12 

Chapter  I.  The  Legal  Status  of  the  Physician  in  Relation  to 
Accident  Insurance  and  Indemnity  for  Accidents 13 

§  I.  The  Legal  Status  of  the  Physician  in  the  United  States  of 
America  and  definition  of  Damages  13  (a). — Indemnity  claims  ad- 
justed according  to  medical  advice  13. — Expert  evidence  in  general 
13. — lledico-legal  experts  13. — Basis  of  expert  testimony  14. — Legal 
measure  of  damages  14  (b). — Nominal  damages  14. — Compensatory 
damages  14. — Factors  entering  into  damages  14. — Earning  ability 
only  fixed  factor  14.  §  2.  Accident  Insurance  in  America  and  Es- 
timatioti  of  Indemnity  for  Accidents  to  the  Eyes  14.- — -Estimates 
by  American  accident  insurance  companies  arbitrarily  figured 
14  (a). — U.  S.  Bureau  of  Pensions  fix  rates  arbitrarily  1(3  (b). 
§  3.  The  German  Accident  Insurance  Law  16 — Provisions  of  the 
act  16. — Explanation  of  its  wording  16. — Inability  to  follow  trade 
only  considered  therein  16. — Indemnification  not  for  injury  itself 
but  for  impairing  of  earning  ability  16.  §  4.  The  Determination 
of  the  Corporal  and  Economic  Damage  from  Injuries  belongs  to  the 
Physician,  Estimation  of  the  Monetary  Compensation  to  the  Cor- 
porations and  the  Courts 17 

Chapter  II.     The  Different  Methods  fob  Estimation  of  Loss  of 

the  Earning  Ability  from  Ocular  Injuries IS 

§  5.  Zehcnder's  Formula  18. — The  formula  and  its  development 
18. — Calculation  improperly  made  with  three  eye  values  IS. — Nor- 
mal man  given  equivalent  of  three  eyes  19. — Formula  cannot  be 
scientifically  applied  19. — Zehender  pioneer  in  mathematical  est'- 
mation  19.  §  6.  Groenouw's  Formula  19  (a). — Explanation  of 
the  fornuila  and  development  19. — Mathematical  consideration  20 
lb). — Contains  two  unknown  quantities  and  is  mathematically  in- 
solvable  20. — He  forces  his  formula  20  (c). — Formula  applied  to 
monocularism  20. — Properly  used  makes  tlie  value  of  vision  in  a 
one-eyed  man  equal  to  nothing  20. — Its  principle  is  improp?r  21. 
Confounds  physiologic  with  anatomic  conditions  21. — Accordingly 
he  makes  human  beings  with  nine  hypothetic  eyes. — Anothfr 
mathematical  view  makes  a  cyclops  21. — The  formula  is  a  fluctu- 
ating equation  and  cannot  be  mathematically  considered  22. 
The  fictitious  values  generalized  by  his  use  of  the  formula  22. — Tlie 
formula  cannot  be  iised  for  scientific  purposes  22.  §  7.  The  For- 
mula of  Hcddaeus  22.  It  is  not  scientifically  constructed  23.  His 
high  estimation  for  the  loss  of  binocular  vision  is  preposterous  23. 
Refutation  of  his  claims 23 


CONTENTS. 


Chapter  III.     §  S.     General  Principles  for  Estimation  of  the  Ee- 

LATiONS  of  Ocular  Injuries  to  the  Earning  Ability 24 

The  ocular  earning  ability  is  one  of  the  corporal  functions  and 
should  be  measured  and  treated  as  such 25 

Chapter  IV.     The  Conception  of  the  Earning  Ability  and  Injuries 

Thereto 23 

§  9.  The  Meaninfi  of  Full  Earning  Abiliti/  2o. — Composition  of  its 
factors  26. — Position  occupied  by  the  ability  to  compete  27. — Work- 
ing ability  not  synonymous  with  earning  ability  28. — A  general 
formula  for  the  full  earning  ability 28 

Chapter  V.  §  10.  Determination  of  the  Amount  of  Injury  to 
THE  Earning  Ability  According  to  ;Magnus  29. — Working  for- 
mula for  the  earning  ability 2D 

Chapter  VI.     §  11.     Estimation  of  the  Damage  to  Economic  Vision     ZO 

The  earning  ability  F  of  our  formula  31. — The  factors  entering 
into  the  visual  act  32. — Relation  of  the  central  visual  acuity  to  the 
ocular  working  ability  32. — Relation  of  the  visual  field  to  economic 
vision  32. — ^Relation  of  tha  ocular  muscles  to  the  visual  field  32. 
Relation  of  the  ocular  muscles  in  monocular  and  binocular  vision 
to  working  vision  33. — Relations  of  these  factors  to  each  other  33. 
Formula  for  binocular  economic  vision  33. — Formula  for  monocular 
economic  vision  33.  §  12.  Estimation  of  the  Economic  Limita- 
tions of  the  Central  Visual  Acuity  33. — Physiologic  and  economic 
limits  not  synonymous  but  vary  according  to  business  demands  34. 
Table  A — The  vaiious  trades  and  professions  arranged  according 
to  their  visual  demands  37. — Group  I — Trades  requiring  higher 
degrees  of  visvial  acuity  37. — Group  II — Ti-ades  requiring  lower  de- 
grees of  visual  acuity  37. — Economic  visvial  limitations  of  railway 
employees  in  Germany  39. — In  America  40.  Table  B — Scitntific 
standard  for  visual  acuity  converted  into  economic  terms:  I.  for 
vocations  demanding  higher  vision;  II.  for  vocations  den:anding 
lower  vision  42. — Descrij^tion  of  Plate  I  for  transposing  the  scien- 
tific standard  of  visual  acuity  into  economic  equivalents  42.  §  13. 
The  Economic  Limits  of  the  Visual  Field  and  Their  Estimation. 
Division  of  the  visual  field  into  three  zones  43.  §  14.  The  Econom  ic 
Relations  of  the  Ocular  Musculature  and  Their  Estimation  44. 
The  muscles  have  their  individual  values 44 

Chapter  VII.     §  1.5.     The  Me.vning  and  Estim.\tion  of  the  Arility 

to  Compete,  K  of  Our  Formula  for  the  Earning  Ability 46 

The  ability  to  compete  is  composed  of  dift'erent  elements  46. — The 
part  that  is  furnished  by  the  individual  himself  47. — The  part  that 
depends  upon  his  employer  or  environment  47. — Special  estimation 
of  the  ability  to  compete  48. — Working  formula 49 

Chapter  VIII.     The  Method  of  C.\lculatio.\  with  the  Formula  of 

Magnus 51 

§  16.  What  does  this  Formula  Mean?  51. — It  is  th^  numerical  ex- 
pression for  the  normal  ocular  earning  ability  51. — On  this  account 
its  mathematical  estimation  must  be  complex  o2.  §  17.  Can  Fi(j- 
uring  with  the  Formula  Be  Made  More  Convenient ?  52. — The  fac- 
tors of  the  formula  may  be  estimated  from  a  mathematically  made 
chart  in  Plate  III  52. — Both  algebraic  estimation  and  the  ratings 
give  the  same  results  53.  §  18.  Calculation  irith  the  Formula 
53. — By  the  use  of  the  curves  in  the  charts  the  estimation  is  made 
a  simple  example  in  multiplication 56 


CONTENTS. 


PART  SECOND. 

Special  Consideration  of  Various  Ocular  Injuries. 

Chapter  IX.     §  19.     The  Eelati\-e  Importance  of  Disturbaxces  of 

THE  Visual  Field   58 

Estimation  of  the  various  forms  of  visual  field  defects  with  remaining 
normal  central  visual  acuity  59. — Summary  in  table  form  61. 
§  20.  Disorders  of  the  Visual  Fields  Complicated  by  Injury  to  the 
Central  Visual  Acuity  of  Different  Degrees  in  Either  Eye  62. 
Rules  for  its  estimation  62. — Auxiliary  data  for  estimation  of  the 
earning  ability  Avhere  the  central  acuitv  of  both  eyes  is  impaired 
differently ' 63 

•Chapter  X.  The  IiiPAiRiiENT  of  the  Earxixg  Ability  FROii  In- 
juries TO  THE  Extrinsic  Ocular  Muscles 65 

§  21.  General  Remarks  Regarding  the  Importance  of  Injuries  to 
the  Extra-Ocular  Muscles  65. — Formula  for  the  Binocular  and 
monocular  acts  of  vision  65.  §  22.  The  Estimation  in  Paralysis 
of  the  muscles  Uncomplicated  by  Other  Visual  Disorders  66. — Damage 
caused  by  paralysis  of  one  rectus  externus  67. — Summary  of  the 
earning  ability  and  impairment  thereof  in  uncomplicated  disorders 
of  the  extrinsic  ocular  muscles  68.  §  23.  Epicritin  Remarks  Con- 
cerning the  Foregoing 69 

Chapter  XL     §   24.     What  Action  Is  Necessary  If  the  Injured 

Person  Has  Previously  Had  the  Use  of  Only  One  Eye? 70 

Scientific  and  economic  monocularism  70. — Mathematical  estimation 
of  original  monocularism  71. — Estimation  of  ability  to  compete  71. 
Formula  for  earning  ability  in  monocularism  71. — Injuries  to  the 
monocular  visual  field 72 

Chapter  XII.  Estimation  of  Accident.\l  Injuries  in  Cases  in 
Which  One  or  Both  Eyes  Did  Xot  Possess  Before  the  Acci- 
dent Si:fficient  Normal  Central  Visual  Acuity 74 

§  25.  The  Meaning  of  Weak  Vision  from  an  Economic  Standpoint. 
74.  §  26.  Estimation  of  the  Earning  Ability  in  Case  Weakness 
of  Vision  Existed  Before  the  Accident  Which  Can  Be  l^^umerically 
Fixed  Through  a  Former  Functional  Examination  76. — ^Modified 
visiial  acuity  76. — Division  of  weakness  of  vision  into  four  groups 
79.  §  27.  Group  I.  One  Eye  Is  Xormal,  the  Other  Originally 
Weak-Sighted.  Five  examples  79.  §  28.  Group  II.  Both  Eyes 
Are  Originally  Equally  Weak-Sighted.  Four  examples  81.  §  29. 
Group  III.  Both  Eyes  Are  Originally  Weak-Sighted  to  a  Different 
Degree.  Four  examples  82  §  30.  Group  IV.  One  Eye  is  Blind, 
the  Other  Originally  Weak-Sighted.     One  example 84 

Chapter  XIII.     The  Loss  of  One  Eye  Through  Accident 85 

§  31.  Estimation  of  the  Vision  in  the  Case  of  Loss  of  One  Eye  85. 
Visual  acuity  85. — The  visual  field  85. — The  muscles  86. — Loss  of 
power  to  estimate  distances,  etc.  86. — Annuity  for  the  loss  of  one 
eye  should  only  be  provisional  86.  §  32.  Estimation  of  the 
Ability  to  Compete  After  the  Loss  of  One  Eye  87.  §  33.  Estimation 
of  the  Earning  Ability  Where  One  Eye  Becomes  Blind  88.  Differ- 
ent valuations  in  monocularism  90. — Decrease  of  annuity  after  one 
year  91. — Revision  of  the  older  rates  91.  §  34.  Concerning  the 
Supposed.  Greater  Danger  of  the  One-Eyed  Person  Becoming  To- 
tally  Blind   and  Its   Relations    to    Indemnity   92.     Danger    from 


CONTENTS. 


atrophy  of  the  optic  nerve  and  ghiucoma  03.     Few  one-eyed  per- 
sons  become   blind   through   injury   93. — Complaints   of    one-eyed 


persons. 


93 


Chapter   XIV.     §    35.     Accidental   Injuries   to    the    Crystalline 

Lens.     Aphakia 94 

Chapter  XV.     §   30.     Injuries  of  the  Eyelids,  Conjunctiva  and 

Cornea 96 

Chapter  XVI.  §  37.  Should  the  Danger  of  Sympathetic  Ophthal- 
mitis Be  Considered  in  Estimating  the  Impairment  of  the 
Earning  Ability 97 

Chapter  XVII.     §  38.     Injuries  of  the  Cornea  Through  Foreign 

Bodies 98 

Chapter  XVIII.  §  39.  Accidental  Impairments  of  the  Accommo- 
dation      99 

Chapter   XIX.     §    40.     Common   Diseases   of   the   Eyes   of   Local 

Origin  That  Impair  the  Earning  Power 100 


PART  THIRD. 

Chapter  XX.  §  41.  Estimation  of  the  Pecuniary  Loss  to  the 
Individual  by  Reason  of  Visual  Imperfections  Resulting  from 
Injuries 104 

Estimation  of  the  relation  between  the  amount  of  visual  acuity 
and  the  loss  of  earning  capacity  104. — The  earnings  of  the  profes- 
sional and  business  man  10.5. — The  earnings  of  the  artisan  105. 
The  earnings  of  the  laboring  class  105. — Table  C  containing  ex- 
amples illustrating  the  monetary  valuation  of  the  remaining  earn- 
ing ability  in  the  case  of  the  average  professional  or  busine^^s  man 
suffering  from  accidental  loss  of  visual  acuity  figured  for  the  five 
decades  of  working  life  106. — Table  D.  the  earning  ability  in  the 
case  of  the  artisan  107. — Table  E.  the  earning  ability  in  the  case 
of  the  laborer  108. — Examples  110-115. — The  use  of  our  rules  and 
tables  for  physicians,  la\\'yers  and  insurance  officials 115 

PART  FOURTH. 

Tables  for  Estimation  of  Different  Forms  of  Damage  to   the   Visual 

Earning  Ability  116 

One  Eye  Xoimal,  the  Other  Injured  but  Not  Blind. 

Table  I.  Vocations  with  higher  visual  demands 117 

Table  II.  Vacations  with  lower  visual  demands 117 

One  Eye  Blind,  the  Other  Weak-Sighted. 

Table  III.  Vocations  with  higher  visual  demands 118 

Table  IV.  Vocations  with  lower  visual   demands 118 

Both  Eyes  Suffering  Injury  of  Equal  or  Different  Degrees. 

Table  V.  Vocations  with  higher  visual  demands 119 

Table  VI.  Vocations  with  lower  visual  demands 120 

Table  VII.  Earning  ability  and  its  impairment  in  disorders  of  the 

visual  field  with  normal  central  visual  acuity....    121 


CONTENTS.  • 

Table  VII  (a)  Ability  to  compete  and  impairment  of  visual  fields  for 
vocations  \<nih  higher  and  lower  visual  demands, 
figured  separately   1"22 

Earning  Ahiliiy  in  Defects  of  Both  Eyes  xvith  Equally  Diminished 
Visual  Acuity. 

Table  VIII.        Vocations  with  higher  visual  demands 123 

Table  IX.  Vocations  with  lower  visual  demands 124 

Table  X.  Earning  ability  and  impairment  from  non-complicated 

disorders  of  the  external  ocular  muscles 125 

Earning  Abiliti/  in   Complicated  Paralysis  of  the  Ocular  Muscles 
u'ith  Disturbances  of  the  Visual  Acuity. 

Table  XI.  Vocations  with  higher  visual  demands 126 

Table  XII.  Vocations  with  lower  visual  demands 126 

Earning  Ability  and  Impairment  in  Disturbances  of  the   Visual 
Acuity  in  an  Originally  One-Eyed  Person. 

Table  XIII.        Vocations  with  higher  visual  demands 127 

Table  XIV.        Vocations  with  lower  visual  demands 127 

Table  XIII  (a)  Earning  ability  and  impairment  if  the  injury  of  one 
muscle  has  to  be  valued  correspondingly  higher,  in 
special  vocations   128 

Earning  Ability  and  Impairment  in  Disturbances  of  the  Visual 
Acuity  in  an  Originally  One-Eyed  Person,  in  a  Scientific  Sense. 

Table  XV.  Vocations  with  higher  visual  demands 129 

Table  XVI.        Vocations  with  lower  visual  demands 129 

Table  XVII.      Earning  ability  and  impairment  in  disturbances  of  the 

visual  field  of  an  originally  one-eyed  person 130 

Table  XVIII.  Of  the  external  ocular  muscles  of  an  originally  one- 
eyed  person 130 

Earni7ig  Ability  of  cwi  Originally  One-Eyed  Person  with  Disturb- 
ances of  the  Visual  Acuity  Complicated  with  Defects  of 
the  Visual  Field,  in  a  Professional  Sense. 

Table  XIX.        Vocations  with  higher  visual  demands 131 

Table  XX.  Vocations  with  lower  visual  demands 131 

Earning  Ability  of  an  Originally  One-Eyed  Person  with  Disturb- 
ances of  the  Visual  Acuity  and  Visual  Field,  in  a  Scien- 
tific Sense. 

Table  XXI.        Vocations  with  higher  visual  demands 132 

Table  XXII.      Vocations  with  lower  visual  demands 132 

Bibliography 135-136 

Alphabetical  Index     139-144 

Plate  II.  Jaeger  test  types  for  near  vision  with  transposition  of  the 
scientific  standard  into  economic  terms. 

Plate  III.  Snellen  test  types  for  distant  vision  with  transposition  of 
the  scientific  standard  into  economic  terms. 

Plate   IV.     Xormal  and  damaged  visual  fields  ^^^ith  economic  valuations. 

Plate  V.  Curves  for  valuation  of  the  visual  field,  of  the  muscular  action 
and  of  the  ability  to  compete. 


PART  FIRST. 


Introduction.  Legal  Status  of  the  Physician  in  Relation 
to  Accident  Insurance  and  Indemnity  for  Accidents. 
Different  Methods  for  Estimation  of  the  Loss  of  Earn- 
ing Ability  from  Ocular  Accidents.  General  Prin- 
ciples for  Estimation  of  the  Relation  of  Ocular  Injuries 
to  the  Earning  Ability.  Conception  of  the  Earning 
Ability  and  of  Injuries  thereto.  Estimation  of  the 
Damage  to  Economic  Vision.  Method  of  Mathe- 
matical Calculation. 


INTRODUCTION. 


As  the  subject  of  which  we  treat  in  the  following  pages  enters 
into  the  domain  of  legal  medicine  and  from  its  technical  side  no 
one  in  America  or  among  English-speaking  peoples  has  yet  had  the 
temerity  to  exhaustively  treat  it,  and  with  the  exception  of  a  brief 
essay  which  the  American  editor  as  chairman  (2)  had  arranged 
for  the  Section'on  Ophthalmology  of  the  American  Medical  Asso- 
ciation and  which  was  ably  given  by  Hansell  (17),  some  medico- 
legal excerpts  and  scraps  here  and  there  in  medical  journals,  the 
literature  is  almost  entirely  German;  we  will,  therefore,  be  obliged 
to  deal  mostly  with  the  facts  and  theories  that  have  been  brought 
forth  b}^  German  writers,  more  especially  those  of  Magnus,  the 
status  of  this  subject  in  xA.merica  in  the  law  courts  with  the  Acci- 
dent Insurance  Companies  and  the  United  States  Pension  office,  and 
then  take  up  the  German  Accident  law,  after  which  we  will  proceed 
to  the  scientific  estimation  of  the  visual  earning  ability. 

In  this  work  we  start  with  the  supposition  that  the  earning 
ability  for  any  gainful  vocation  requiring  eye  sight  is  practically 
synonymous  Avith  the  visual  earning  ability,  and  that  injuries  to 
the  eyes  affecting  the  vision  have  a  direct  detrimental  effect  upon 
the  earning  capacity  of  the  individual  (See  Chap.  lY.,  §  9,  p.  26; 
Chap.  YL,  §  11,  p.  30;  Chap.  YI.,  §  12,  p.  36).  It  is  self-evident 
that  a  totally  blind  person  is  absolutely  incompetent  to  work  at  any 
trade  or  in  any  profession  which  demands  eye-sight,  and  that  the 
vast  majority  of  blind  people  are  not  only  incapable  of  earning 
anything,  but  are  a  charge  upon  their  families  and  upon  the 
community.  But  even  the  blind  man,  provided  that  he  has  had  the 
necessary  education  and  experience,  need  not  remain  absolutely 
idle  or  be  perfectly  dependent ;  for  in  some  vocations  where  the  use 
of  the  mental  powers  is  the  chief  factor,  such  as  banking,  some  mer- 
cantile pursuits  and  professions  where  knowledge  may  be  assimi- 
lated through  the  eyes  of  others  or  by  methods  peculiar  to  the 
blind  and  by  the  actual  work  being  done  by  employees,  some  spe- 
cially well  placed  and  talented  individuals  may  continue  to  be 
economic  factors.  But  these  are  exceptions,  and  there  can  be  no 
doubt  that  the  possession  of  good  eye-sight  is  the  prime  factor  for 
full  earning  abilitv  for  the  greater  majority  of  gainful  human 

2 


12  INTRODUCTION. 


vocations,  and  any  injury  to  it  is  usually  followed  by  a  lessening 
of  the  earning  ability  and  of  the  resultant  compensation.  We  con- 
sider that  with  laborers  or  artisans,  in  fact  any  of  the  so-called 
working  classes,  who  may  by  accident  acquire  some  defect  of  eye- 
sight, ranging  from  partial  to  complete  blindness  in  one  or  both 
eyes,  that  the  effect  of  this  visual  defect  upon  the  earning  ability 
will  be  identical  with  the  percentage  of  the  loss  of  eye-sight  or 
visual  earning  ability. 

A  decision  of  this  character  has  not  yet  been  reached  in  Ameri- 
can courts  of  law,  but  we  have  no  doubt  that  it  must  soon  be  made, 
and  when  such  a  precedent  is  established,  the  damage  to  economic 
vision  will,  in  every  case,  be  estimated  in  a  scientific  manner  and  be 
given  a  prominent  position  in  judging  the  amount  of  damages  to 
be  allowed  in  personal  damage  suits,  of  which  a  considerable  num- 
ber relate  to  the  eyes.  We  likewise  hope  that  the  factor  of  visual 
economic  damage  will  be  sometime  taken  into  consideration  in 
insurance  circles  and  by  the  United  States  government  in  estab- 
lishing the  rates  of  insurance  and  pension  annuities.  We  are  con- 
vinced that  this  factor  has  been  estimated  in  the  following  pages 
in  a  scientific  manner  and  we  confidently  assert  that  in  any  given 
case  where  the  eyes  have  been  injured  we  can  figure  the  amount 
of  damage  to  the  earning  ability.  It  is  fortunate  that  the  state 
of  ophthalmic  science  allows  of  a  definite  estimation  of  the  working 
powers  of  the  eye.  This  is  not  so  in  respect  to  other  corporal  func- 
tions, for  instance,  the  economic  loss  of  an  arm  or  a  leg  or  the  loss 
of  the  sense  of  smell  or  of  hearing  certainly  cannot  be  as  exactly 
estimated  as  that  of  the  sense  of  sight.  Upon  the  latter  depends 
our  earning  power  and  the  others  but  partially  and  temporarily  af- 
fect it.  Gainful  occupations  may  only  be  followed  when  the  sense 
of  sight  and  the  mental  faculties  are  unimpaired.  The  loss  of  the 
visual  powers  invariably  has  a  deleterious  effect  upon  the  calling 
dependent  upon  the  degree  of  damage  and  the  nature  of  the  voca- 
tion which  may  be  shown  in  dollars  and  cents. 

The  work  that  we  present  may  perhaps  establish  a  standard  for 
the  use  of  courts  of  law  and  accident  insurance  companies,  which 
now  have  no  uniform  methods  of  estimating  the  value  of  an  in- 
dividual's sight. 


EXPERT   EVIDENCE.  13 


CHAPTER  L 


THE   LEGAL   STATUS   OF    THE   PHYSICIAN  IN   RELATION   TO 

ACCIDENT  INSURANCE  AND  INDEMNITY 

FOR  ACCIDENTS. 


§1.     The  Legal  Status  of  the  Physician  in  the  United  States  of  America 
and  Definition  of  Damages. 

Most  indemnity  claims  in  America  are  adjusted  according  to 
the  opinion  of  a  reputable  physician,  more  especially  on  the  advice 
of  the  official  medical  adviser  or  examiner  of  the  insurance,  traffic 
or  manufacturing  company,  or  of  the  U.  S.  Pension  office  physi- 
cian, or  upon  the  s-vvorn  statements  of  those  deputized  for  exami- 
nation of  the  special  case,  with  the  exception  of  contested  cases 
and  suits  for  damages,  etc.,  which  are  settled  in  the  courts  of  law. 
In  most  of  the  States  of  the  Union,  the  physician  or  oculist  may 
be  compelled  to  testify  as  a  common  witness  or  may  be  brought  into 
the  case  as  an  expert;  in  either  event  he  may  be  required  to  give 
expert  testimony. 

The  principles  of  expert  evidence  and  medico-legal  expert  testi- 
mony are  outlined  by  Sinkler  (Baudry  4)  as  follows : 

(a)  As  TO  Expert  Evidence  in  General. — A  principle  of  the 
law  of  evidence  is  stated  by  an  authority  on  the  subject  as  follows : 
''The  fact  that  any  person  is  of  opinion  that  a  fact  in  issue  does 
or  does  not  exist  is  deemed  to  be  irrelevant"  (Stephen  42).  But 
the  same  writer  notes  an  exception  to  this  rule.  "Matters  of 
opinion  are  admissible."  "Where  there  is  a  question  as  to  any 
point  of  science  or  art,  the  opinions  upon  that  point,  of  persons 
specially  skilled  in  any  such  matter,  are  admissible."  The  words 
science  or  art  are  taken  to  include  all  subjects  on  which  a  course 
of  special  study  or  experience  is  necessary  to  the  formation  of  an 
opinion.  "But  opinions  of  experts  are  admissible  only  in  relation 
to  their  art,  and  not  as  to  matters  of  common  knowledge." 

Medico-legal  Experts. — The  opinions  of  medical  men  are  con- 
stantly admitted  as  to  the  cause  of  disease  or  death  or  the  conse- 
quences of  wounds,  or  the  treatment  of  sickness ;  and  as  to  the  sane 
or  insane  state  of  a  person's  mind  as  collected  from  a  number  of 
circumstances,  and  as  to  other  subjects  of  professional  skill  (Tay- 
lor 43.)  But  his  special  knowledge  must  be  established  and  his 
examination  confined  thereto  (Greenleaf  9.)  "A  physician  may 
testify  as  to  cause  of  death  (or  disease),  from  personal  examination 
or  knowledge,  but  his  testimony  extends  no  further  than  the  im- 
mediate cause,  because,  manifestlv.  that  is  the  limit  of  science." 
(Wis.  Eepts.,  Vol.  101,  p.  278.)   (50) 


14  DAMAGES. 


As  TO  What  Should  Form  the  Basis  of  the  Expert's  Testi- 
mony in  a  particular  case;  the  opinion,  to  be  admissible,  must  be 
founded  either  on  his  own  personal  knowledge  of  the  facts  testified 
to  in  court  or  upon  an  hypothetical  question  (Bell  6.)  His  evi- 
dence as  to  facts  must  be  the  result  of  his  own  examination.  A 
physician  may  not  give  his  opinion  as  to  a  case  in, which  he  was 
called  into  consultation  and  where  his  knowledge  of  the  case  is 
derived  solely  from  the  discussions  with  his  fellow-consultant.  A 
physician's  opinion  is  not  admissible  if  based  on  statements  made  to 
him  by  parties  out  of  court  and  not  under  oath  (Lewis  23.) 

(b)  Legal  Measure  op  Damages. — Damages  is  defined  by 
Taylor  (44)  as  "the  injury  or  loss  for  which  compensation  is 
sought,"  and  the  measure  of  damages  refers  to  the  amount  or  ex- 
tent of  such  injury  or  loss.  Three  distinct  kinds  are  recognized 
and  awarded  to  suit  the  merits  of  the  case : 

First.  ISToMiisrAL  Damages,  or  some  trifling  sum  which  is 
awarded  when  a  breach  of  duty  or  infraction  of  the  plaintiff's  right 
is  shown,  but  no  serious  loss  is  proven  to  have  been  sustained. 
Such  are  awarded  for  violation  of  a  plaintiff's  right,  but  where  no 
damages  are  shown  by  the  evidence. 

Second.  Substantial  or  Compensatory  Damages. — These 
are  such  as  are  designed  and  awarded  to  compensate  for  the  actual 
loss  or  injury  sustained.  The  jury  weighs  the  evidence  and  fixes 
the  amount  which  in  their  opinion  properly  compensates  the  in- 
jured party  for  the  loss  suffered. 

In  this  work  only  the  after-effects  of  the  accident,  the  economic 
damage,  is  figured.  In  addition  to  this,  American  courts  allow  the 
amount  actually  expended  in  the  necessary  treatment  following  the 
accident,  the  monetary  valuation  of  the  time  lost,  the  amount  of 
injury  to  the  business  of  the  individual,  and  indemnity  is  claimed 
and  allowed  for  tlie  mental  effect,  the  pain  and  anguish  suffered 
by  reason  of  the  accident.  The  amounts  of  all  these  factors  are 
arbitrarily  allowed  together  by  the  courts.  The  only  factor  that 
can  he  fixed  with  scientifi.c  exactness  is  the  actual  loss  to  the  earning 
ability  which  follows  the  accident,  the  estimation  of  tvhich  is  the 
business  of  this  hooh  and  which  should  be  the  principal  basis  fori 
settlement  of  all  claims. 

Third.  Exemplary  or  Punitive  Damages,  also  termed  vin- 
dictive. This  class  exceeds  the  loss  actually  sustained,  and  is  given 
as  a  kind  of  punishment  to  the  defendant. 

§3.     Accident  Insurance  in  America  and  Estimation  of  Indemnity 
for  Accidents  to  the  Eyes. 

(a)  The  Estimates  Made  by  the  American  Accident  In- 
surance Companies  are  now  based  upon  empiric  ideas  and  the 
results  of  experience,  such  as  the  proportion  of  eye  injuries  to  those 


RULIXGS   OF   ACCIDENT   IXSURAXCE   COMPAXIES.  15 

of  the  other  parts  of  the  body,  upon  the  ratio  of  losses  to  the  whole 
number  of  insured,  and  upon  the  amount  of  premium  the  insured 
is  willing  to  pay  in  ordinary  risks.  In  other  words,  the  general 
principle  of  insurance  is  the  foundation  for  the  incurring  and  set- 
tlement of  eye  cases  (Hansell  17.)  For  example:  "When  the 
loss  or  partial  loss  of  vision  totally  disables  the  insured  from  per- 
forming all  his  duties,  total  disability  is  paid.  When  it  disables 
him  from  performing  one  or  more  of  his  duties,  partial  disability 
is  paid.  This  ruling  naturally  holds  in  cases  of  disability  from 
other  than  ocular  causes"  (Preferred  Mutual.)  The  Travelers' 
Insurance  Co.  said:  "There  is  no  general  method  of  estimating 
the  pecuniary  disability  in  cases  of  partial  loss  of  vision  for  several 
reasons.  One  will  sutfice.  Xo  accident  policy  ever  written  has 
undertaken  to  estimate  such  disability.  On  the  contrary,  the  in- 
surance contract  is  either  a  valued  policy,  fixing  a  definite  sum  in 
the  event  of  loss  of  vision  in  one  or  both  eyes,  or  it  names  a  definite 
sum  to  be  paid  as  weekly  indemnity  for  total  or  partial  loss  of  time 
resulting  from  eye  injuries."  The  Aetna  Co.  replied :  "The 
method  of  estimating  pecuniary  indemnity  in  cases  of  partial  or 
complete  loss  of  vision  from  accident,  depends  upon  the  form  of 
2X)licy  which  the  insured  has  purchased.  If  his  occupation  is  such 
as  to  entitle  him  to  insurance  in  the  select  or  preferred  class,  the 
indemnity  payable  for  total  loss  of  sight  of  both  eyes  woiild  be 
ec|ual  to  the  full  amount  of  his  insurance,  being  therefore  placed 
upon  the  same  basis  as  a  fatal  accident.  The  loss  of  the  entire 
sight  of  one  eye  is  compensated  for  by  the  payment  of  one-eighth 
the  amount  that  would  be  paid  for  the  loss  of  both  eyes.  If  the 
loss  of  sight  is  partial  (temporary')  and  its  temporary  loss  results 
in  the  insured  being  unable  to  perform  the  duties  of  his  occupation, 
he  is  indemnified  for  such  loss  of  time  simply,  just  as  though  he 
were  injured  in  any  other  organ.  As  to  loss  of  vision  from  dis- 
ease: under  our  special  health  policy  provision  is  made  that  in 
such  an  event  an  amount  equal  to  100  weeks'  indemnity  for 
total  disability  will  be  payable.  Payments  made  bv  insurance  com- 
panies for  such  loss  Avere  originallv  arbitrarily  fixed  and  the  ex- 
perience of  the  companies  has  not  been  of  such  nature  as  to  make 
it  necessary  to  modify  the  same  materially." 

Thus  bv  agreement  between  the  insurance  companies  and  the 
insured,  the  former  assume  the  risk  of  being  called  upon  to  pay 
sums  ranging  from  $600  to  $1,000  for  one,  and  $5,000  for  the  loss 
of  both  eyes,  provided  the  insured  pays  a  certain  yearly  sum.  The 
amount  is  determined  by  the  ratio  of  eye  injuries  to  injuries  of 
other  parts  of  the  body  and  to  fatal  injuries,  taken  from  a  large 
number,  and  the  willingness  of  the  insured  to  pay  a  yearly 
premium  commensurate  with  his  own  conception  of  the  pecuniary 
value  of  an  eye  and  of  vision  and  of  the  risk  he  believes  he  incurs. 
This  is  a  purely  mutual  and  financial  arrangement  and  is  made  in- 
dependently of  age,  sex,  occupation  (excluding  special  risks)  and 
annual  income. 


16         U.  S.  BUREAU  OF  PENSIONS — GERMAN  LAW. 


(b)  The  United  States  Bureau  of  Pensions  has  fixed  the 
rates  of  pension  for  disability  arising  from  disease  of  the  eyes  thus : 
"Total  blindness  of  both  eyes  $72.00  per  month;  loss  of  one  eye 
$17.00  per  month;  loss  of  sight  of  one  eye  $12.00  per  month.  In 
cases  of  disease  of  eyes  causing  defective  vision,  the  rates  vary 
from  $6.00  to  $50.00  according  to  rank  and  pay."  (17) 

§3.     The  Oerman  Accident  Insurance  Law. 

July  6,  1884,  there  was  an  accident  insurance  law  passed  (von 
Woedtke  46)  which  is  now  in  force  in  the  German  Empire.  §  5 
defines  its  intention  as  follows:  Compensation  for  the  loss  re- 
sulting from  bodily  injury  or  death  is  to  be  adjusted  according 
to  the  following  provisions : 

1.  The  cost  of  necessary  treatment  commencing  at  the  begin- 
ning of  the  14th*  week  after  the  accident. 

2.  A  regular  income  to  be  paid  to  the  injured  person  from  the 
beginning  of  the  14th  week  during  the  time  of  his  inability 
to  work. 

The  wording  of  the  law  shows  that  neither  the  injury  itself 
nor  any  temporary  results,  such  as  the  detention  from  work  or  the 
expense  of  treatment  up  to  the  14th  week  thereafter,  is  considered 
grounds  for  indemnification,  but  it  relates  solely  to  the  effects  when 
they  have  had  a  more  permanent  detrimental  influence  upon  the 
earning  powers. 

Section  II,  §  5  shows  that  the  law-makers  had  nO'  other  inten- 
tion and  the  law  should  not  be  interpreted  in  any  other  sense.  The 
law  does  not  mean  that  under  all  circumstances  injured  persons 
should  receive  indemnification. 

We  agree  with  Mooren  (29,  p.  29)  when  he  says,  "The  presence 
of  an  ocular  imperfection  does  not  constitute  a  claim  for  indemni- 
fication, but  only  the  existence  of  inability  to  follow  a  trade  or 
profession  resulting  from  such  imperfection  can  be  so  considered." 
If  the  physician  desires  to  do  his  duty,  he  cannot  depart  from  this 
interpretation  of  the  law.  While  there  is  no  doul)t  that  the  effect 
of  this  Accident  Insurance  Law  is  not  to  indemnify  the  insured  for 
the  injury  itself,  but  only  for  the  impairing  of  the  earning  ability, 
it  has  not  yet  been  definitely  decided  who  shall  be  the  authority 
for  determining  the  extent  of  this  loss  of  earning  ability  and  es- 
pecially the  amoamt  of  the  indemnification.  Some  claim  that  this 
is  the  duty  of  the  physician,  others  that  it  is  the  exclusive  right 
of  the  courts  and  the  insurance  officials. 

•It  will  be  noted  that  this  Insurance  Law  deals  only  with  the  results  of  accidental 
injuries  after  14  weeks  have  elapsed  from  the  date  of  the  accident.  The  reason  for  this  may 
lie  in  the  fact  that  most  German  manufacturers  pay  their  City  Hospitals  certain  sums, 
(which  have  been  retained  from  the  workman's  wages)  for  the  care  of  their  sick  employees 
and  indemnification  for  accidents  is  considered  due  only  after  the  lapse  of  14  weeks. 

What  is  an  eye  worth  in  America  ?  To  any  of  us  sisht  is  priceless,  but  the  courts 
award  from  $1,0(10.00  to  $8,000.00,  the  latter  being  the  highest  indemnity  yet  given.  See  Dela 
Vergne  Refrigerator  Co.  vs.  Stahl,  Court  Civil  Appeals,  Texas,  1901,  Journal  A.  M.  A.,  1901. 


DETERMINATION"    OF   DAMAGE   BY   PHYSICIANS.  17 


§4.  The  Determination  of  the  Corporal  and  Economic  Damage 
from  Injuries  Belongs  to  the  Physician,  the  Estimation  of 
the  Monetary  Compensation  to  the  Corporations  and  the 
Courts. 

Foerster  (7,  p.  16)  considers  that  the  duty  of  the  physician  is 
only  to  attest  to  the  kind  of  injury,  leaving  the  estimation  of  its 
effect  upon  the  earning  ability  to  the  trade  assoiciation.  To  this 
we  cannot  agree;  for  instance;  what  help  will  it  be  to  the  in- 
surance officials  or  to  the  average  juryman  if  we  inform  them 
that  a  certain  injured  person  has  suffered  from  "a  paralysis  of  the 
musculus  externus  sinistra?"  In  order  to  properly  judge  of  the 
relations  between  the  laming  of  an  ocular  muscle  and  the  earning 
capacity,  technical  physiologic  knowledge  is  certainly  needed,  and 
verily,  we  cannot  expect  a  tradesman  to  have  a  scientific  mind. 
A  physician  can  much  sooner  acquire  a  knowledge  of  the  technical 
peculiarities  of  the  different  trades  than  the  trade  association  can 
get  even  a  modicum  of  medical  knowledge.  There  are  but  few 
vocations  with  which  a  physician  does  not  come  in  contact.  Wag- 
ner (38,  p.  21)  states  that  it  is  the  duty  of  the  physician  to  acquire 
some  knowledge  of  the  trades  of  the  patients  with  whom  he  deals, 
as  by  this  means  he  is  enabled  to  estimate  the  relation  of  the  injury 
to  the  loss  of  the  earning  ability.  To  the  foregoing  we  heartily 
agree.  It  is  the  province  of  the  physician  to  estimate  the  propor- 
tional loss  to  the  earning  ability  resulting  from  disease  or  trauma- 
tism, for  who  among  men  is,  from  his  training  and  daily  work,  so 
well  qualified,  and  whose  business  brings  him  into  closer  relations 
with  such  economic  problems?  The  question  of  monetary  com- 
pensation, the  sordid  matters  of  dollars  and  cents,  may  be  left  to 
the  business  corporations  and  the  courts  of  law. 


18  zehender's  formula. 


CHAPTER  IL 


DIFFERENT    METHODS    FOR    ESTIMATION    OF    LOSS    OF    THE 
EARNING  ABILITY  FROM  OCULAR  INJURIES. 


§0.     Zehender's  Formula. 

Zehender  was  the  first  who'  tried  to  make  a  rule  for  the  esti- 
mation of  the  loss  of  the  earning  powers  from  ocular  injuries  (53.) 
His  publication  provoked  a  series  of  papers  by  other  German  writ- 
ers who  declared  that  liis  premises  were  incorrect  and  his  calcu- 
lations illogical.  We,  therefore,  give  a  critical  resume  of  the 
several  methods  of  mathematical  computation  that  have  been  pro- 
posed, showing  their  errors,  and  then  proceed  to  the  exposition  of 
the  method  of  Magnus,  which  for  accurate  scientific  work  seems 
to  us  to  be  the  most  satisfactory.  Zehender  gave  a  formula  founded 
upon  a  suppositious  case  where  the  sight  of  one  eye  is  entirely 
lost  while  that  of  the  other  remains  normal.  He  supposed  that 
such  a  normal  eye  acquires  a  much  higher  value  (even  double) 
than  formerly. 

To  compute  the  amount  of  vision  left  after  the  loss  of  one  eye 

by  his  method,  three  eye  values  must  be  considered,  two  for  the 

normal  eye  and  one  for  the  blind  one,  which  he  places  in  the  form 

2  ><  1  +  0       2 
of  an  arithmetical  equation  thus,  =  -^,  The  visual 

faculty  in  such  a  ease  is,  therefore,  two-thirds  of  normal. 

If  Zehender's  supposition  be  right  and  if  after  the  loss  of  one 
eye,  we  really  had  to  figure  with  three  quantities,  there  would  be 
nothing  to  say  against  its  correctness,  but  it  is  arithmetically  in- 
correct in  its  conception,  for,  if  we  double  the  value  of  any  object, 
we  do  not  make  by  this  manipulation  two  different  ones  but  one 
which  is  only  of  a  different  value  and  therefore  by  such  an  equa- 
tion applied  to  eye  values  we  only  change  the  quality  of  the  two 
eye  values,  the  number  remaining  the  same.  Although  this  fact 
may  be  self-evident,  we  will  exemplify  it  as  follows :  Supposing 
a  man  owns  a  house  which  thro'ugh  some  fortunate  event  would  be- 
come twice  as  valuable  as  formerly,  would  anybody  believe  in  this 
ease  that  the  man  now  owns  two  houses?  Let  us  vary  this  ex- 
ample and  suppose  that  this  man  owns  two  houses  of  equal  value, 
one  of  these  increases  in  value  to  double,  the  other  through  some 
accident  depreciates  entirely,  would  anybody  conceive  the  idea  that 
this  particular  man  now  owns  three  houses  or  claim  that  he  would 
have  to  figure  with  three  houses  in  the  valuation  of  his  property? 
Zehender  however  has  come  toi  such  a  curious  conclusion,  so  that, 
by  his  formula,  we  would  have  to  figure,  in  the  case  of  the  one- 
eyed  man,  with  three  eye  values.     He  has  made  a  one-eyed  person 


GROENOUW'S   FORMULA.  19 

into  a  three-eyed  one.  Zehender's  error  is  in  supposing  that  he 
really  creates  by  the  enhanced  valuation  of  one  thing,  a  new  and 
second  self-existing  object.  Thus,  if  we  woaild  express  the  earn- 
ing ability  by  his  speculative  proposition  and  arithmetical  example, 
but  avoiding  his  serious  mathematical  and  logical  errors,  the  for- 

2-1-0 
mula  would  be :      rni^i  *     ^^^'  ^^  ^^^^  formula  would  give  for  the 

earning  ability,  notwithstanding  the  loss  of  one  eye,  the  full  value 
O'f  one,  the  consequence  is  that  Zehender's  expression  cannot  be 
used  in  the  proper  mathematical  way.  Thus  Zehender's  formula 
belongs  only  to  history.  jSTevertheless,  he  should  be  accorded  the 
honor  of  having  first  shown  that  the  mathematical  method  is  the 
correct  way  for  estimation  of  the  ocular  earning  ability. 

§6.     GroenoHw's  Formula. 

(a)  Groenouw  (12,  p.  34)  uses  a  formula  which  likewise  does 
not  give  the  normal  physiologic  and  economic  value  for  vision,  but 
like  that  of  Zehender's,  it  rests  upon  a  pathologic  process  of  injury 
to  the  faculty  of  sight.  He  begins  with  the  supposition  that  the 
stronger  eye  possesses  a  greater  economic  value  than  the  weaker 
one.  If  the  difference  of  the  visual  powers  of  the  eyes  be  some- 
what great,  then  the  better  eye  would  alone  be  accustomed  to  work 
while  the  weaker  would  count  very  little  in  regard  to  earning  abil- 
ity.    Groenouw  expresses  this  supposition  l)y  taking  first  an  arith- 

O-pi       I       op 

metical  proportion  of  the  visual  power  of  both  eyes,  ,    -.      in 

which  Se  stands  for  the  better  and  se  for  the  poorer  eye,  and  by 
this  formula  the  better  eye  (Se)  is  given  m  times  greater  value 
than  the  poorer  one.     We  would  therefore  transpose  the  foregoing 

formula  into  ^L><S^_±^.       He  also  adds  to  this  expression  the 

M  -f  1 
value  of  the  visual  field  P  making  the  expression  for  the  earning 

,.,.,     ^       mXSe  +  se^ 
abilitv,  E  = r^ P. 

'  M  +  1 

As  Groenouw's  formula  does  not  represent  the  value  of  normal 
physiologic  vision  for  earning  purposes  but  rather  the  value  of  an 
already  pathologically  changed  faculty,  therefore,  it  cannot  be 
used  for  a  general  expression  of  economic  vision  but  only  for  some 
certain  special  case.  In  Groenouw's  equation  E  stands  for  the 
earning  ability  which  is  the  unknown  quantity  and  the  results  to 
be  sought  by  all  the  equations  considered  in  this  book,  m  stands 
for  the  greater  value  acquired  bv  the  sound  eye  after  injurv  to  its 
fellow.  This  enhancement  is  likewise  unknown.  Se  is  the  cen- 
tral visual  acuity  of  the  better  eye  which  can  be  ascertained  by 
functional  examination,  se  is  the  visual  acuity  of  the  poor  eve 
which  is  likewise  to  be  found.  P  is  the  value  of  the  visual  field 
which  can  be  ascertained.     We  have  now  in  Groenouw's  formula  an 


20  GROENOUW'S   rOEMULA   INAPPLICABLE. 

equation  with  two  unknown  quantities,  E  and  ]\r,  and  three  known 
quantities,  Se^  se  and  P.  But  such  an  equation  has  numberless 
solutions,  as  it  is  possible  to  compute  from  the  values  given  to  one 
unknown  quantity  separate  values  for  the  other  (the  exceptions  are 
only  the  so-called  diophantic  equations  which  cannot  be  considered 
in  this  connection.)  As  this  formula  admits  of  numberless  solu- 
tions we  ma}'  therefore  consider  it  inapplicable  for  our  purpose, 
for  we  would  be  unable  to  tell  which  of  the  numberless  possibilities 
would  be  the  right  one  in  a  given  case.  An  equation  which  is  able 
to  give  a  single  precise  answer  is  the  only  practical  one.  Thus, 
from  the  very  start,  with  his  equation  containing  two  unknown 
quantities,  Groenouw  got  into  a  desperate  position  because  he  pro- 
posed a  formula  which  cannot  be  treated  in  a  correct  mathe- 
matical manner. 

(b)  The  estimation  of  ocular  damage  by  Groenouw's  formula 

.     ,,        •  •     1  p  -n       M  X  Se  +  SE  „  .        ,         ., , 

m  the  original  form,     E  = r^, P  is  not  possible, 

°  M  +  1  ^ 

because  the  two  unknown  quantities  contained  therein  cannot  be 
figured  out  of  this  one  formula.  Groenouw,  however,  extricates 
himself  out  of  tliis  disagreeable  situation  by  forcibly  pressing  his 
formula  into  a  more  desirable  form,  which  allows  of  a  certain  kind 
of  estimation  of  the  damage  to  central  and  peripheric  vision.  Be- 
fore we  can  take  up  the  subject  of  these  cases  in  which  there  is 
partial  damage  to  the  visual  faculty  but  no  actual  blindness,  we 
must  first  regard  the  working  of  this  formula  in  the  case  of  a 
one-eyed  man. 

(c)  We  are  of  the  opinion  that  Groenouw's  formula  cannot  be 
properly  used  in  the  ease  of  monocular  vision :  For  he  conceives 
that  there  is  a  certain  proportional  value  between  the  ]x>wer  of 
sight  ill  the  better  and  that  of  the  poorer  eye,  the  better  eye  having 
M  times  earning  value  over  that  of  the  poorer  (12,  pp.  35,  36,  37), 
i.  e.,  that  the  better  eye  (13)  exercises  an  m  times  greater  influ- 
ence upon  the  earning  ability  than  the  poorer,  but  if  one  eye  is  en- 
tirely blind,  this  proportional  valuation  is  simply  impossible  be- 
cause a  blind  eye  is  never  of  any  assistance  to  the  earning  ability 
and  does  not,  therefore,  possess  an  earning  value;  then  the  poorer 
€ye  cannot  have  an  m  times  greater  value  than  the  blind  one,  for 
the  earning  value  of  the  blind  eye  is  equal  to  nothing,  and  m  times 
this  is  also  nothing;  therefore,  the  mathematical  rule  which 
shows  that  the  multiplication  of  a  number  value  with  naught  makes 
it  alwavs  l)ecome  naught,  render?  Groenouw's  calculation  a  mathe- 
matical absurdity,  in  that  according  to  his  rules  a  one-eyed  person 
must  be  entirely  incapable  of  earning  anything. 

In  Groenouw's  formula  E,  the  earning  ability,  and  :m,  the  en- 
hancement of  the  earning  value  of  the  better  eye,  is  unknown. 
Se.  the  sight  of  the  healthy  eye,  equals  1 ;  se.  the  sight  of  a  totally 
blind  eye,  disappears  entirely  out  of  the  formula  :  P,  the  visual  field, 
is  given  by  him  a  value  of  9-10,  which  has  been  found  by  exact 


GROENOUW'S  FORMULA.  21 


physiological  examination  and  wliicli  we  will  here  accept  in  a  case 
of  monocular  vision,  Groenouw  constructs  the  following  formula: 

M  +  1 

This  formula  is  constructed  in  an  arithmetical  equation  similar 
to  that  of  Zehender's.  As  long  as  both  eyes  could  see,  the  better 
63^6  with  the  power  Se  would  have  m  times  value  over  and  above 
the  poor  eye,  se^  thus  the  numerator  of  the  arithmetical  equation 
would  be:MXSE+SE.  But  if  one  eye  grows  blind,  its  faculty  of 
seeing  is  then  entirely  omitted,  the  numerator  then  becomes  m  X  Se 
or  because  Se  is  1  it  equals  ii ;  the  simplified  formula  thus  being : 

E  =  ^P. 

M  +  1 

If  the  value  se^  one  of  the  two  values  out  of  which  the  arith- 
metical proportion  is  formed,  is  entirely  omitted,  its  influence  is 
•exerted  not  only  in  the  numerator  but  in  the  denominator  of  our 
fraction.  Thus  the  numerator  of  the  formula  would  be  reduced 
to  M  +  0,  as  the  numerical  earning  value  of  the  blind  eye  is  o. 
Whether  a  blind  eye  is  in  the  head  or  has  been  removed  by  an  opera- 
tion is  entirely  foreign  to  this  subject,  as,  if  it  is  blind,  it  must  be 
regarded  as  non-existing  as  far  as  it  relates  to  the  earning  ability 
and  must  be  treated  accordingly  in  the  denominator  of  the  arith- 
metical proportion,  which  is,  therefore,  m  +  o.  Groenouw,  however, 
■calls  the  denominator  m  +  1,  whether  one  eye  can  be  counted  or  not, 
and  thus  in  the  formula  which  should  represent  solely  the  physio- 
logic earning  value  rates  a  blind  and  therefore  non-existing  eye 
with  a  positive  earning  value  of  1. 

Groenouw  has  confounded  the  physiologic  with  the  anatomic  con- 
ditions; for  the  physiologic  purposes  a  blind  eye  is  practically  the 
same  as  if  it  were  non-existing,  and  because  he  has  done  so  he  pre- 
sents in  the  further  course  of  his  calculations  with  human  beings 
who  have  theoretically  nine  seeing  eyes,  for  instance,  in  a  concrete 
ease  in  which  one  eye  has  visual  acuity  of  ^  and  the  other  l/l ,  the 

8  +  -  +  - 
earning  ability  is  expressed  thus :     E  = * ^  1,  and  this  is 

nothing  else  but  the  arithmetical  proportion  of  the  faculty  of 
vision  of  a  being  who  has  nine  seeing  eyes.  The  outrage  upon  com- 
mon sense  is  none  the  less  if  the  human  being  be  likened  to  a  cyclops 
or  to  a  nine-eyed  monster.  One  of  the  two  suppositions  has  to  be 
chosen  if  Groenouw's  formula  be  used,  because  it  does  not  admit 
of  the  consideration  of  a  normal  being  having  two  seeing  eyes. 
"We  have  shown  that  the  text  of  Groenouw's  formula  is  erroneous 
and  will  now  regard  the  manner  in  which  he  uses  it  to  express  the 
earning  abilitv  of  the  one-eved  person,  for  which  his  formula  is, 

E  =  ^P.' 

M  +  1 


22  FORMULA    OF    IIEDDAEUS. 

In  this  formula  E  and  the  enhancement  of  value  of  the  sound 
eye,  :m,  are  unknown.  Here  is  again  an  equation  with  two  un- 
known quantities  which  has  no  fixed  but  numberless  solutions. 
Such  mathematical  difficulties  are  passed  over  by  Groenouw  in  the 
following  manner:  He  first  supposes  that  the  income  of  a  one-eyed 
person  is  33  I/3,  therefore  the  earning  ability  must  be  3-^  ,  and  with- 
out any  reflection  he  inserts  this  arbitrary  value  into  his  formula 

M 

thus :  ^  =  — r--  Mo.    In  this  equation  m  can  be  figured  with- 
M  + 1  ^  *= 

out  any  difficult}^,  which  would  be  about  3.     But  we  can,  of  course^ 

have  as  great  a  number  of  values  for  m  as  that  for  E,  but  for 

which  Groenouw  has  made  an  arbitrary  valuation,  ys  or /^  (7,p.35), 

and  which  anybody  has  the  privilege  of  changing.     If  we  would 

figure  b}^  his  method,  we  would  form  such  a  fluctuating  equation 

that  E  could  not  be  mathematically  considered. 

(d)  Groenouw  further  handles  these  doubtful  and  fictitious  val- 
ues in  the  following  way :  For  the  estimation  of  injuries  in  which 
the  central  visual  acuity  has  been  injured,  but  total  blindness  not 
resulting:  Here  he  does  not  hesitate  to  generalize  the  values  for 
M  which  he  forced  into  his  equation  in  the  case  of  one-eyedness 
and  uses  them  in  the  calculation  of  other  cases  in  which  both  eyes 
see,  despite  the  fact  that  the  value  of  the  vision  in  the  seeing  eye 
in  one-sided  blindness  is  quite  different  from  that  of  the  better  eye 
in  another  case  where  some  sight  remains.  The  earning  ability 
of  a  one-eyed  person  is  quite  a  different  thing  from  the  earning 
abilit}'  of  a  normal  being,  and  these  terms  are  not  interchangeable. 
Thus,  Groenouw's  formula,  being  based  upon  fictitious  values  and 
improperly  formed,  cannot  be  used  for  the  scientific  estimation 
of  the  economic  value  of  vision. 

§7.     The  Formula  of  Heddaeus. 

Heddaeus  (18)  bases  his  calculations  upon  the  indisputable 
fact,  that  if  the  faculty  of  sight  be  reduced  to  one-half,  the  re- 
mainder represents  a  proportional  greater  amount  of  earning  ability 
than  that  which  has  been  lost.  This  observation  causes  him  to  sup- 
pose that  the  loss  of  earning  power  is  equal  to  the  square  of  the  loss 
of  Wsion.  We  cannot  see  Avhy  only  the  square  and  not  the  cube 
or  the  fourth  or  any  other  power  should  not  designate  the  above 
proportion.  This  is  simply  an  arbitran-  decision  of  Heddaeus  and 
is  not  founded  on  the  real  proportion.  In  his  writings,  he  does 
not  give  any  mathematic,  physiologic  or  economic  proofs  of  the 
correctness  of  his  proposition.  Heddaeus  makes  one  assertion  to 
which  we  must  most  emphatically  protest,  for  he  brings  the  factor 
of  binocular  vision  in  connection  with  ocular  injuries  into  a  most 
unwarrantably  prominent  ])osition.  In  the  case  of  acquired  mo- 
nocular vision  from  accidents,  he  asserts  that  the  diminution  of  the 
earning  abilitv  is  onlv  affected  bv  the  loss  of  binocular  vision  and 


FORiLULA  OF  HEDDAEUS  INAPPLICABLE.  23 

that  this  factor  and  the  loss  of  the  power  to  estimate  distances 
correctly,  is  the  most  essential  factor  for  the  loss  of  the  earning 
power.  This  supposition  is  ridiculous !  Although,  immediately 
after  the  loss  of  one  eye,  the  faculty  for  estimation  of  distance 
and  size  of  objects  is  lost  for  a  while,  and  is  detrimental  to  the 
earning  ability,  and  therefore  should  not  be  underestimated,  it  dis- 
appears entirely  in  a  comparatively  short  time. 

By  examinations  (Magnus  26,  p.  38)  of  the  one-eyed  laborers 
among  the  iron  and  steel  workers  in  Silesia,  it  was  found  that  fully 
70  per  cent,  of  those  who  were  blinded  in  one  eye  had  learned  to  see 
■easily  and  estimate  distances  correctly.  As  this  faculty  is  restored 
to  every  one,  it  needs  only  passing  consideration. 


24  GENERAL  PRIXCIPLES   OF   MEASUREMENT. 


CHAPTER  III. 


§8.     General  Principles  for  Estimation  of  the  Relations  of  Ocular 
Injuries  to  the  Earning  Ability. 

The  fact,  that  during  the  last  few  years  so  many  different 
propositions  for  the  estimation  of  the  economic  value  of  vision  have 
been  proposed,  shows  that  the  general  principles  involved  in  deter- 
mining the  earning  ability  are  not  yet  clearly  understood.  We  will,, 
therefore,  search  for  and  explain  certain  general  principles  for 
this  estimation  which  will  serve  as  a  basis  for  that  relating  to  the 
visual  act  which  is  one  of  the  functions  of  the  general  organization. 
We  will  give  the  visual  earning  ability  a  prominent  part  in  our 
considerations. 

If  in  a  given  case  we  desire  to  mathematically  determine  the 
amount  of  power  of  any  bodily  function,  we  first  have  to  find  a 
general  expression  for  the  normal  ability  of  the  particular  organ. 
We  usually  determine  such  expression  by  taking  the  average  of  a 
large  number  of  measurements  of  the  particular  function  and 
designate  this  average  as  an  expression  of  the  normal  powers.  In 
this  way  we  have  formed  the  standard  of  visual  acuity,  of  the  visual 
field,  of  the  normal  light  and  color  sense,  etc.  Starting  from  this 
average  value,  we  measure  the  power  of  the  organ  in  any  special 
case.  The  difference  between  its  power  and  our  standard  is  a 
fraction  which  in  the  case  under  examination  may  represent  the 
amount  of  damage  done  to  the  function.  This  we  do  in  the  estima- 
tion of  the  pathologic  diminution  of  central  visual  acuity  and  with 
limitations  of  the  visual  field.  When  we  succeed  in  creating  such 
an  average  normal  value  of  the  function  of  an  organ  or  bodily 
power,  we  can  then  estimate  the  amount  of  individual  acts,  as  if 
measuring  a  piece  of  cloth  with  a  yard-stick.  This  method  is  used 
in  the  other  natural  sciences  as  well  as  in  medicine.  Therefore,  we 
must  first  fix  an  expression  for  the  normal  ocular  earning  ability 
before  we  can  estimate  the  amount  of  individual  cases.  The  objec- 
tion that  the  application  of  this  principle  to  the  act  of  vision  and 
the  resultant  measurements  Avould  be  arbitrary,  holds  good  to 
but  a  limited  extent,  for  where  a  conception  of  the  normal  func- 
tion has  been  developed  from  a  series  of  definite  measurements 
from  which  the  average  value  has  been  estimated,  we  do  not  speak 
arbitrarily,  especially  where  this  conception  has  been  upheld  by 
other  findings,  the  products  of  searching  inquiries  of  a  scientific 
character;  but  we  must  remember  that  a  function  of  a  body  or  a 
natural  power  is  a  need  which  cannot  be  weighed  with  the  scales 
or  measured  bv  the  yard,  and  therefore  we  cannot  entirely  do  with- 
out certain  arbitrary  suppositions. 


GENERAL   PRINCIPLES  OF  MEASUREMENT.  25 

In  our  opinion  thei'e  is  only  one  way  for  the  establishment  of  a 
formula  for  the  normal  ocular  earning  ability,  and  that  is,  by  the 
separate  estimation  of  the  value  of  each  physiologic  factor  form- 
ing the  sense  of  sight,  and  by  the  addition  of  these  component  parts 
the  normal  value  of  vision  may  be  established.  The  construction 
of  such  a  formula  is  facilitated  by  the  fact  that  we  already  have 
established  the  physiologic  value  for  the  more  important  factors 
entering  into  the  visual  act,  i.  e.,  the  central  visual  acuity  and  the 
field  of  vision.  But  the  normal  physiologic  act  of  vision  is  a  com- 
posite quantity  formed  of  different  factors  which  have  more  or  less 
relation  to  the  economic  value  of  the  eye.  We  may  exclude  those  ■ 
factors  which  are  without  economic  importance  for  the  salce  of  our 
subject.  We  thus  form  out  of  the  composite  act  of  seeing  a  reduced 
or  economic  estimation  of  the  visual  act.  In  order  to  do  this  we 
must  fuse,  bring  into  or  eliminate  certain  of  these  factors  to  satisfy 
our  purpose.  As  we  have  placed  the  visual  earning  act  in  a  normal 
position  (chap.  IV.,  §  9),  we  will  use  the  same  method  for  deter- 
mination of  its  factors.  Damaged  ocular  earning  ability  will  al- 
ways be  considered  as  a  fraction  of  the  normal  power.  This 
method,  which  permits  of  a  mathematical  estimation  of  each  por- 
tion of  the  visual  act  as  a  fraction  of  the  normal,  must  be  consid- 
ered to  be  complete,  as  it  is  in  perfect  harmony  with  the  principles- 
laid  down  by  the  natural  sciences  in  measuring  the  work  of  any 
organ  or  power. 

Judging  by  this  standard,  we  must  consider  that  the  proposi- 
tions of  Zehender,  Groenouw  and  Heddaeus  were  on  the  wrong  track 
from  the  very  start.  None  of  these  authors  developed  an  expres- 
sion for  the  normal  physiologic  act  of  vision.  Their  formulae  for 
expressing  the  economic  value  of  vision  stand  absolutely  on  patho- 
logic grounds  and  they  introduce  self-constructed  pathologic  sup- 
positions into  the  calculations,  instead  of  looking  at  the  earning 
ability  as  a  quantity  resulting  from  a  combination  of  the  different 
parts  composing  the  physiologic  act  of  vision.  Thus  these  for- 
mulae are  not  expressions  for  existing  conditions,  but  are  nothing 
but  the  mathematical  sediment  of  intuitions  arbitrarily  conceived 
by  these  authors.  As  they  have  departed  from  the  physiologic  and 
only  reliable  ground  for  arbitrary  hypotheses,  their  theories  are 
shown  to  conflict,  in  a  most  humorous  manner,  with  the  physiologic 
ocular  conditions  in  a  healthy  person.  Thus,  according  to  Zehen- 
der's  calculation,  a  human  being  would  have  three  seeing  eyes,  and 
Groenouw  acts  as  if  nature  had  given  him  nine  eyes  or  put  him  into 
the  world  as  a  eyclops. 


26  THE  EARXIXG  ABILITY. 


CHAPTER  IV. 


THE  CONCEPTION  OF  THE  EARNING  ABILITY  AND  INJURIES 

THERETO. 


§9.     The  Meaning  of  Full  Earning  Ahility. 

If  we  would  conceive  of  an  injury  to  the  earning  ability  as  a 
quantity  which  can  be  given  a  mathematical  value,  we  would  have 
to  start  from  an  estimation  of  the  complete  earning  ability,  which 
in  a  healthy  normal  individual  is  a  comj^osite  quantity  resulting 
from  three  factors  : — 

(1)      The  unimjjaired  functional  power  of  the  bodily  organs. 

(2).  The  technical  knowledge  which  is  necessary  for  the  carry- 
ing on  of  the  vocation. 

(3).  The  ability  of  the  individual  to  compete  in  the  labor 
market. 

In  an  opinion  given  by  the  Imperial  Insurance  office  Xov.  26, 
1887  (Becker  5,  p.  10),  the  meaning  of  the  earning  ability  is  thus 
stated : 

''In  judging  the  earning  ability  the  bodily  and  intellectual  con- 
dition of  the  injured  person  has  to  be  considered  in  connection 
•with  the  preparatory  education  and. also  his  capacity  for  earning 
a  living."  In  this  definition,  "bodily  and  intellectual  condition," 
is  the  same  as  the  first  of  our  elements  (1),  the  unimpaired  func- 
tional ability  of  the  bodily  organs ;  the  so-called  "preparatory  edu- 
cation," would  correspond  with  our  (2),  the  technical  knowledge 
necessar}'  to  the  calling;  and  our  (3),  the  capacity  or  ability  to 
compete  in  the  labor  market,  is  defined  in  the  official  definition  as 
^'capacity  for  earning  a  living." 

These  elements  cannot  be  regarded  as  equal  in  value.  Doubt- 
less the  functional  condition  of  the  bodily  organs  is  of  the  first  im- 
portance for  successful  work.  The  preparatory  education  or  knowl- 
edge is  of  nearly  equal  value.  Much  less  importance  should  be 
given  to  the  third  element,  the  ability  to  compete  in  the  labor 
market.  This  is  dependent  upon  the  value  of  the  two  others,  be- 
cause the  ability  of  an  artisan  to  battle  against  competition  de- 
pends largely  upon  the  condition  of  his  health  and  his  technical 
knowledge — our  two  first  elements.  We  have  divided  the  concep- 
tion of  the  earning  ability  into  its  three  fundamental  elements 
solely  because  such  an  analysis  makes  it  possible  to  put  the  normal 
earning  ability  into  a  mathematical  formula.  Thus  we  designate 
the  eamincr  ability  itself  E ;  the  first  of  our  elements,  the  func- 
tional abilitv.  F ;  the  second,  the  necessary  knowledge,  Y ;  and  the 
third,  the  ability  to  compete.  K.  In  this  formula  we  put  the  two 
quantities,  F  and  Y,  in  their  full  value  and  accept  K  as  a  root 


FACTORS  OF  EARNING  ABILITY.  27 


value.  There  would  be  nothing  c-haaiged  in  the  total  value  of  the 
formula  itself  because  as  the  root  of  1  is  always  1,  and  we  regard 
F,  V  and  K  as  1,  it  is  immaterial  for  the  formula  itself  if  we 
take  one  of  the  three  quantities  as  a  root  or  not,  but  this  proportion 
immediately  changes  when  the  part  introduced  as  a  root  grows 
smaller  than  1,  as  happens  in  each  ocular  injury,  because  the  root 
of  each  genuine  fraction  is  always  greater  than  the  fraction  itself. 
Thus  the  influence  of  K,  after  being  introduced  as  a  root  value,  if 

K  K 

it  has  fallen  off  by  an  injury  to  -      cannot  be  any  more 

but  must  be  greater,  for  instance,  "       .     Therefore,  the  damage  to 

the  total  value  of  the  formula  will  be  smaller  if  we  take  K  as  a 
root  value.  By  the  total  elimination  of  K  the  earning  ability 
will  not  be  diminished,  but  it  will  be  by  a  smaller  damage,  according 
to  the  influence  the  damage  of  K  shall  exercise  upon  the  value  of  the 
total  formula.  We  will  have  to  choose  the  exponent  of  the  root 
as  smaller  or  greater,  according  to  its  rating.  The  value  of  a  root 
of  a  genuine  fraction  is  much  great^*  if  its  exponent  is  small. 
Therefore,  if  we  wish  to  lower  it  considerably,  we  take  a  small,  if 
we  wish  to  effect  it  less,  a  greater  exponent  for  Iv.  While  the 
ability  to  compete,  K,  is  comparatively  very  little  impaired  through 
minor  ocular  injuries,  it  is  very  much  so  through  the  loss  of  one 
eye;  we  suit  these  conditions  by  choosing  a  greater  exponent  of 
the  root  in  slight  injuries,  but  a  smaller  exponent  for  serious  ones. 
We  will  adopt  for  the  slight  injuries  K  as  the  10th  root  and 
for  serious  ones  according  to  the  demands  of  the  profession, 
the  7th  root  or  the  oth  root.  We  will  more  fully  explain  this  in 
one  of  the  following  chapters.  An  exact  calculation  of  such  a 
changeable  quantity  so  dependent  upon  the  individual  cannot  be 
made.  The  calculation  of  the  competing  ability  cannot  be  waived 
entirely,  as  does  Groenouw,  who  submits  in  each  case  the  estimation 
of  this  important  factor  to  the  pleasure  of  the  examiner.  We  have 
started  out  to  make  a  practical  mathematical  formula,  but  should 
include  all  factors  that  are  relative;  as  we  will  show  further  on,  the 
peculiarities  of  the  individual  case  may  ahvays  be  considered. 

When  we  express  the  earning  ability  through  the  three  factors, 
F,  Y  and  Iv,  we  present  E,  not  as  a  sum.  but  as  the  product  of  these 

X 

quantities,  as  multiplied  thusly :  E=FVV'  K,  in  which  the  exponent 
X  changes  with  the  degree  of  the  functional  damage.  E  must  al- 
ways be  regarded  as  a  product  and  not  as  a  sum,  to  meet  all  possi- 
bilities occurring  in  practice.  If  Ave  add  F.  Y  and  Iv,  the  formula 
would  give  wrong  practical  results,  as  we  see  in  the  following  ex- 
ample: Supposing  both  eyes  were  lost  in  an  accident,  the  quantity 
F  of  our  formula  would  be  0.     If  we  had  connected  F,  Y  and  K 

with  the  +,  flncl  added,  even  if  K  would  have  become  0,  Y  -\-V  K^ 
which  is  the  remainder  of  the  eamins-  abilitv.  would  have  been  left. 


28  -WORKING  ABILITY  AND  EARNING  ABILITY. 


This  would  be  entirely  wrong,  because  a  lalwrer  who  has  lost  his 
functional  ability,  especially  the  sense  of  sight,  should  be  regarded 
in  an  optical  way  as  entirely  unable  to  earn.  Taking  the  same  ex- 
ample and  using  our  formula  with  F=0,  E  immediately  becomes 
0,  because  each  product  is  always  0  if  one  of  the  factors  is  0.  If 
we  would  leave  Y  out  of  our  formula,  E  of  course  =0,  and  actual 
practice  confirms  this,  because  even  the  most  simple  hand  work 
requires  a  certain  amount  of  preparatory  education.  Finally,  if 
we  drop  the  third  factor,  the  10th  root  of  K,  the  normal  earning 
ability  according  to  our  formula  becomes  0,  which  is  likewise 
shown  by  practical  experience,  because,  even  though  an  indi\ddual 
is  in  good  health  and  by  reason  of  preparatory  education  has  the 
skill  to  work,  if  his  work  is  not  needed,  his  economic  value  is  nil. 
He  may  possess  the  power  of  working,  as  the  factors  F  and  V  are 
present,  but  he  only  has  earning  ability  when  he  can  dispose  of  the 
work  in  the  economic  market.     Therefore,  if  from  our  formula 

(E=F  V  K  K  )  we  take  away  the  factor  V  K  (the  ability  of  the 
individual  to  dispose  of  his  work),  the  remainder,  which  is  the  for- 
mula for  the  working  ability  (A),  would  be  A==F  V. 

The  "working  ability*"  is  not  synonymous  with  "earning  ability," 
although  some -authors  would  have  it  so,  for  instance,  Becker 
(5,  p.  9)  :  "The  words  "working  ability'  and  'earning  ability' 
may  be  regarded  identical  in  meaning,  because  in  each  worker  the 
latter  depends  upon  the  former.''  Even  if  this  be  so,  the  two  con- 
ceptions are  not  the  same,  and  such  a  rendition  obscures  the  concep- 
tion of  the  earning  ability,  our  definition  of  which  should  be 
clearly  understood. 

The  calculation  of  injury  to  the  earning  ability  proposed  by 
us  starts  from  the  formula  for  the  full  earning  ability : 

E  =  F  V  K  K. 


DAMAGE  TO  EARNING  ABILITY.  29 


CHAPTER  V. 


§10.     Determination  of  the  Amount  of  Injury   to   the  Earning 
Ability  According  to  Magnus. 

When  one  or  more  of  the  factors  forming  the  earning  ability 
is  injured,  an  idea  of  the  amount  of  damage  to  it  may  be  formed 
if  we  first  consider  to  what  extent  tlie  single  factors  are  injured. 
We  will  find  that  the  application  of  mathematics  to  tliis  subject 
will  prove  somewhat  complicated,  as  we  will  have  to  first  separately 
■estimate  the  damage  to  the  different  factors  and  then  fix  the  value 
of  the  total  formula.  Under  certain  conditions,  this  task  may 
become  decidedly  complicated,  as  some  of  these  factors  forming  the 
complete  earning  ability  are  composed  of  several  elements  which 
have  to  be  figured  separately.  This  is  especially  the  case  with  the 
act  of  seeing  (F  of  our  formula),  which,  as  we  will  see  directly, 
•consists  of  three  separate  parts,  each  of  which  may  be  damaged  in 
a  different  way.  To  ascertain  the  value  of  the  factor  F,  we  have  to 
solve  three  mathematical  problems,  but  in  return,  our  method  of 
•estimation  does  not  alone  offer  the  possibility  of  giving  a  mathe- 
matical expression  to  the  different  forms  of  damage  to  the  ocular 
apparatus,  but  also  allows  us  to  do  this  in  an  accurate  manner, 
with  due  consideration  of  the  different  individual  conditions  in 
■question,  and  finally  our  method  solves  the  mathematical  prob- 
lems (chap.  Ill,  §8)  in  a  satisfactory  manner.  It  starts  from 
the  physiologic  ocular  earning  ability  and  designates  the  damage 
thereto  as  fractions  of  the  normal  value,  making  our  method  right 
in  its  principle  and  easy  to  comprehend.  The  calculation  of  our 
formula  is  simplified  by  the  fact  that  our  factor  V  (the  prepara- 
tory education),  may  be  entirely  cut  out  in  estimating  injury  to 
the  earning  ability.  As  important  as  this  factor  may  be  to  the 
normal  earning  ability,  we  may  put  it  aside  in  a  case  of  accidental 
damage.  The  technical  education  in  itself  will  not  be  injured  di- 
rectly. It  is  only  indirectly  affected  by  accidental  injury.  Cer- 
tainly the  visual  function  may  be  diminished  to  such  an  extent  that 
the  realization  of  the  technical  knowledge  becomes  limited,  but  this 
injury  to  the  earning  ability  in  such  a  case  does  not  rest  upon  a 
diminution  of  the  knowledge  and  the  capacity,  biit  limitation  of 
their  use.  We  calculate  the  extent  of  such  limitation,  according  to 
our  method,  directly  bv  the  factor  F,  i.  p.,  from  the  performance 
of  the  visual  act,  which  is  the  essential  factor  in  the  full  eaminij 
ability,  damage  to  which  is  synonymous  with  damage  to  the  total. 
Calculating  F  we  have  already  used  Y.  For  simplicity's  sake 
it  would  be  better  to  omit  T  entirely.     The  n'orl-tng  formula  for 

X 

the  earning  ability  then  would  be :  E=F  V  K. 


30  VISUAL  FACTORS. 


CHAPTER  VI. 


§11.     Estimation  of  the  Damage  to  Economic  Vision. 

Normal  physiologic  vision  consists  of  a  series  of  difEerent  fac- 
tors :  the  central  acuity,  the  visual  field,  light  and  color  senses,  the 
adaptive  faculty,  the  muscular  movements  and  the  cerebral  proc- 
esses^ all  acting  together  in  creating  the  sense  of  sight.  We  may, 
therefore,  regard  the  act  of  seeing  as  a  sum  whose  numerals  are 
formed  by  the  different  functions;  if  one  numeral  be  taken  from 
the  sum  which  represents  the  complete  act  of  seeing,  then  the 
balance  will  be  left,  i.  e.,  vision  will  be  damaged  to  the  extent  of  the 
loss  of  one  of  these  visual  functions;  but  vision  is  yet  in  existence 
in  a  limited  way.  In  the  manufacture  of  a  formula  for  physiologic 
vision  we  would  have  to  consider  that  in  losing  simultaneously  the 
two  most  important  factors,  central  and  peripheric  vision,  the  act 
of  seeing  would  be  nil ;  but  from  an  economic  standpoint  we  could 
not  get  along  with  this  idea.  The  different  secondary  functions 
forming  sight  have  different  valuations.  In  calculating  the  injury 
to  the  visual  earning  ability  we  will  have  to  exclude  cerebral  vision 
because  accidental  injuries  affecting  the  cerebral  centers  will  hardly 
ever  be  of  such  limited  extent  that  the  valuation  thereof  would  be 
done  by  an  oculist.  In  such  a  case  the  neurologist  would  be  de- 
manded. The  sense  for  light  and  color  and  that  of  adaption  are 
not  themselves  to  be  considered  in  estimating  accidental  damage 
to  the  ocular  earning  ability.  An  injury  limited  exclusively  ta 
these  functions  is  not  known.  Theoretically  such  injuries  might 
be  possible,  but  practically  they  are  not  recognized.  Such  trau- 
matisms would  generally  be  connected  with  disturbance  of  other 
portions  of  the  visual  act,  especially  that  of  visual  acuity  and  the 
visual  field.  Therefore,  we  include  the  functions  of  the  light  and 
color  sense  and  of  the  adaptive  power,  when  we  treat  of  the  dis- 
turbances of  the  visual  acuity  and  visual  field,  as  thereby  the  estima- 
tion is  rendered  less  complicated.  The  visual  acuity,  the  field  of 
vision  and  the  muscular  movements  are  of  so  much  more  impor- 
tance that  we  think  we  can  properly  estimate  the  results  of  ocular 
traumatisms  by  taking  into  consideration  only  these  latter  three. 
These  are  to  be  regarded  as  the  factors  of  a  product  and  multiplied. 
Practical  experience  shows  us  that  we  must  do  this  under  all  cir- 
cumstances, because  for  the  following  of  a  vocation,  none  of  these 
factors  could  be  damaged  or  left  out,  for  without  them  the  earning 
ability  would  disappear.  If  a  person  loses  the  central  acuity  of 
both  eyes,  then  we  certainly  have  complete  earning  disability;  not 
even  the  common  laborer  having  lost  his  central  acuity  could  do 
his  former  work.  Such  an  individual  could  only  take  very  low 
grade  positions,  such  as  that  of  a  messenger.     The  possibility  of 


VISUAL  FACTORS.  31 


doing  much  work  in  the  several  trades  after  the  loss  of  central 
acuity  is  so  completely  excluded  from  consideration,  that  it  would  be 
extremely  incorrect  if  we  did  not  consider  an  artisan  who  had  a 
large  central  scotoma,  i.  e.,  lost  his  central  visual  acuity,  entirely 
unable  to  pursue  his  vocation  and  earn  anything.  If  peripheric 
vision  is  lost  in  both  eyes,  working  at  trades  is  likewise  excluded,  as 
is  readily  seen  in  cases  of  double-sided  hemianopsia.  A  working 
man  with  total  paralysis  of  all  the  outer  ocular  muscles  is  likewise 
totally  disabled.  In  such  a  case  he  Avill  stare  into  vacancy  and 
cannot  work  in  a  binocular  manner.  He  would  lose  the  ability  to 
estimate  distances  and  the  size  of  objects,  and  could  only  have  a 
certain  degree  of  monocular  vision,  which  could  be  imagined  to  be 
useful  only  in  certain  special  cases,  as  that  of  a  nearsighted  clerk. 
Such  a  ease  might  be  looked  upon  as  a  curiosity  and  would  be 
rather  an  exception,  so  that  it  could  not  be  used  to  refute  our  view 
that  the  ocular  muscles  are  absolutely  necessary  for  the  earning 
ability.  Even  the  closing  of  one  eye,  which  Groenouw  holds  in  readi- 
ness as  a  remedy  for  the  restoration  of  the  earning  ability,  will 
help  nothing,  for  the  other  will  stare  immovably  if  its  muscles  are 
paralyzed.  The  adjustment  that  is  noted  in  congenital  defects 
cannot  be  likened  to  that  of  acquired  ones  and  cannot  be  considered 
in  their  influence  upon  the  earning  ability.  The  physiologic  process 
out  of  which  an  adjustment  and  an  increase  up  to  the  earning 
ability,  which  has  been  asserted  by  Groenouw  (13)  to  have  occurred 
in  a  case  of  acquired  paralysis  of  all  the  ocular  muscles,  is  certainly 
very  strange  to  us.  Therefore,  in  the  case  of  an  artisan  with  an 
acquired  paralysis  of  all  the  outer  ocular  muscles  there  is  total 
disability  to  work. 

In  building  up  a  formula  for  the  act  of  seeing  in  relation  to 
earning,  we  denominate  the  central  acuity  with  the  letter  C  and 
the  visual  field  with  P.  The  valuation  of  the  muscular  motions, 
M,  offers  certain  difficulties,  because  the  influence  of  a  distur- 
bance of  the  function  in  a  single  ocular  muscle,  from  a  professional 
standpoint,  is  quite  a  different  one,  AA'hether  we  take  into  considera- 
tion monocular  or  binocular  vision.  The  monocular  act  is  but 
slightly  affected  by  paralysis  of  one  ocular  muscle,  as  it  only  dimin- 
ishes the  motility  of  the  eyeball,  but  in  binocular  vision  the  factor 
of  diplopia  comes  in  and  this  is  of  the  greatest  importance,  as  it 
excludes,  temporarily  at  least,  retention  of  working  binocular  vision. 
In  formation  of  our  formula  wo  would,  therefore,  treat  the  factor 
of  muscular  movements  in  a  different  manner,  when  treating  of 
binocular  vision,  than  we  would  for  the  monocular  act.  In  the 
formula  for  binocular  vision  we  take  the  muscular  movements  of 
each  eye  as  the  product  of  different  factors,  each  of  which  corres- 
ponds to  the  activity  of  a  particular  muscle.  Now,  if  we  mark  the 
muscles  of  one  eye  with  (  mi  m-z  m.{  m^  ms  mc  )  and  those  of 
the  other  (    mi'    m^     ms'    m,'    ms'    me'    )  etc.,  we  would  represent 


32  THE  VISUAL  FIELD  AXD  OCULAR  MUSCLES. 


the  whole  muscular  activity  as  (mi  m2  irirj  m*  ms  me)  (m/  m./  m/ 
m/  m^''  me')-  ^^  this  conception  the  whole  product  would 
be  0,  by  losing  one  single  muscular  motion,  and  therefore 
the  binocular  act  would  be  negative.  In  monocular  vision  the  mus- 
cular activity  should  be  conceived  as  the  sum  of  the  single  per- 
formances, because  by  losing  one  of  them  only  an  ocular  detriment 
has  been  created  and  not  total  earning  disabilit}',  thus  mi  +  mj  + 
ms  +  mi  +  ms  +  me- 

A  few  remarks  about  the  relations  of  the  different  fac- 
tors entering  into  the  visual  act  are  here  advisable.  The 
central  visual  acuity  is,  under  all  circumstances,  the  most  important 
element  for  the  function  of  vision.  Any  injury  which  reduces  the 
central  visual  acuity  below  the  lowest  limits  required  in  the  pro- 
fession, produces  a  total  disability  for  that  work.  Peripheric 
vision  is  of  less  importance  and  has  not  as  much  influence  upon  the 
visual  act,  and  injuries  to  it  have  a  smaller  influence  to  the  entire 
act  of  vision  than  the  degree  of  injury  of  the  visual  field  itself.  If,  for 
instance^  the  remaining  peripheric  vision,  P,  should  be  denominated 

Y 

with  a  greater  fraction  than  — ,  Ave  may  do  this  by  introducing  P 
as  a  root  value  like  we  did  with  the  factor  K  for  the  earning  ability 

Y  Y 

(Chap.  IV,  §  9).    The  root  of  —  would  then  be  greater  than  -^ 

2y  ^  ^ 

for  instance        .     The  damage  to  the  total  value  of  the  formula 
X  *= 

would  be  smaller,  if  P  be  taken  as  a  root  value  and  the  value  of  the 
act  of  vision  would  not  be  diminished  to  the  value  of  P,  but  to  a 
smaller  extent. 

The  same  is  the  case  with  the  action  of  the  muscles,  but  even  to- 
a  greater  extent,  as  they  are  much  less  important  for  the  monocu- 
lar act  of  vision  than  is  the  visual  field.  We  will,  therefore,  add 
the  action  of  the  muscles  M  as  a  root  value  in  the  formula,  but  we 
will  take  the  exponent  of  this  root  to  be  much  greater  than  the 
exponent  of  the  root  value  of  the  visual  field.  According  to 
mathematical  principles  the  value  of  the  root  of  a  proper  fraction 
increases  with  the  amount  of  its  exponent,  thus,  if  we  introduce 
M  with  a  greater  exponent  of  the  root  than  P,  in  the  case  of  damage 
to  M,  it  will  exercise  less  influence  upon  the  total  value  of  the 
formula.  We  believe  that  we  may  place  the  relative  value  of  the 
visual  field  and  the  muscular  movements  by  choosing  as  exponent 
of  the  root  in  the  former  2,  and  in  the  latter  4.  Of  course,  these 
are  arbitrarily  chosen,  as  it  is  an  undisputed  fact  that  the  central 
visual  acuity,  peripheric  vision  and  the  muscular  movements  have 
different  nieanings  in  the  act  of. vision,  the  proportional  valuation 
of  which  cannot  be  put  into  figures  from  observation  nor  from  meas- 
urement, it  is  certainly  allowable  for  the  mathematician  or  the  phy- 
sician to  estimate  the  amounts  of  these  exponents  differently,  but 
the  formula  itself  will  not  be  changed.     We  thus  reserve  for  the 


FORMULA    FOR    BINOCULAR   AND    MONOCULAR    VISION.  33 


examiner  in  each  case,  the  right  to  make  allowance  for  his  individ- 
ual conception,  which  factor  we  regard  as  a  great  advantage  in  our 
method.     Thus  our  formula  for  the  hinocular  act  of  vision  would 


be :  S2  ^  C  V'  P  V  (mi  mz  ms  m*  m5  me )  ( m/  m/  m/  m/  m/  me' ) 

In  this  formula  C  is  considered  the  central  visual  acuit}^  in  the 
better  eye,  which  under  normal  conditions  will  always  equal  1. 

In  case  of  double-sided  damage  to  the  visual  acuity,  if  we  desire 
to  condense  this  formula  into  that  for  the  monocular  act,  we  should 
consider  that  the  peripheric  vision  as  well  as  the  activity  of  the 
extra  ocular  muscles  M,  enter  into  the  monocular  act  in  a  some- 
what different  form.  The  monocular  field  of  vision  is  a  fraction 
smaller  than  the  binocular.  It  is  commonly  only  ^  (Groeuouw  ^o) 
of  the  latter.  (An  exhaustive  explanation  of  these  conditions  will 
be  found  in  the  chapter  treating  of  monocular  vision.)  The  extra- 
ocular muscles  have  smaller  value  in  monocular  vision  than  in 
binocular,  because  in  the  former  those  functions  of  the  outer  mus- 
culature of  both  eyes  that  are  essential  in  estimating  distance  and 
the  relations  of  objects,  etc.,  are  missing.  Therefore,  we  here  con- 
sider the  value  of  the  musculature  as  less  and  estimate  it  at  ^  of 
the  binocular  value.  This  smaller  valuation  of  M  may  be  ulti- 
mately neutralized  if  a  monoculism  caused  by  accident  has  existed 
a  considerable  period.  We  compute  the  formula  for  the  monocular 
act  of  vision  from  the  binocular  one  as  follows : 


Si  =  C  Vye  P  V  ^.(mi  +  m.,  +  ms  +  m*  +  ms  +  me.) 

§12.     Estimation   of   the  Economic   Limitations   of    the   Central 
Visual  Acuity. 

The  central  acuity  lies  within  well-known  physiologic  limits. 
When  it  falls  below  these,  the  function  itself  is  damaged,  but  the 
conditions  met  with  in  practice  are  not  such  that  the  physiologic 
and  earning  limitations  of  the  central  visual  acuity  are  interde- 
pendent; if  it  were  so,  the  claim  of  Zehender  (53,  p.  266)  would 
stand ;  then  the  smaller  the  damage  of  the  former,  the  greater  the 
earning  value  of  the  latter,  and  vice  versa.  If  we  desire  to  have  a 
general  rule  for  the  ability  of  every  single  ocular  function,  an  aver- 
age value  must  be  found  by  many  single  measurements,  but  such 
average  values  permit  of  many  exceptions  and  cannot  be  designated 
as  the  average  limiting  value  of  the  earning  ability,  for.  if  such  were 
the  case,  each  variation  therefrom  might  be  termed  a  damage  to  the 
earning  ability.  This  may  be  done  by  individual  measurement  of 
each  factor  ineach  case,  but  such  always  bears  an  individual  stamp. 
We  must  not  forget  that  while  the  limit  values  of  every  function 
have  a  scientific  meaning,  the  conditions  met  in  actual  practice  are 
different.  Science  calls  an  individual  blind  only  when  perception 
of  light  has  entirely  disappeared,  but  in  actual  practice,  he  is  blind 
if  the  faculty  of  sight  has  been  weakened  to  such  an  extent  that 


34  ECONOMIC   MEANING   OF  BLINDNESS. 


the  organ  of  Aision  cannot  be  used  to  earn  a  living  (Magnus  24); 
The  meaning  of  blindness  as  used  in  daily  life  is  much  narrower 
than  that  of  science. 

Xow  and  then  extremely  great  demands  may  be  made  upon 
the  action  of  certain  organs  which  may  reach  to  its  highest  ability. 
Jn  actual  practice  we  are  satisfied  with  the  amount  of  labor  which 
does  not  strain  the  powers.  Zehender's  (53,  p.  266)  principle,  that 
the  full  earning  ability  existed  only  Avith  full  acuity  of 
vision  and  every  diminution  of  the  highest  limits  means 
at  the  same  time  a  diminution  of  the  earning  ability, 
cannot  be  accepted.  Xot  alone  do  we  raise  scientific 
scruples  against  the  acceptance  of  a  proportional  relation  be- 
tween the  earning  ability  and  the  scientific  meaning  of  visual 
acuit}',  but  also  practical  experience  is  entirely  against  such  rela- 
tion. There  is  hardly  any  vocation  Avhich  demands  the  extreme 
limit  of  sight  (according  to  scientific  figures),  as  a  condition  of 
success.  In  each  vocation  a  great  many  individuals  may  be  found 
who  have  comparatively  poor  sight  but  the  same  earning  ability 
as  those  with  normal  eyes  (Groenouw  11).  Josten  (20,  p.  526)  is 
correct  when  he  says  that  Zehender  shifted  with  his  principle  not 
alone  the  limits  of  the  earning  ability,  but  created  a  new  and  arti- 
ficial meaning.  Neither  the  lowest  nor  the  highest  points  of  sci- 
entific visual  acuity  correspond  with  that  used  in  business;  the 
lowest  point  of  the  latter  is  not  as  low  as  the  lowest  point  laid 
down  by  science,  while  the  highest  point  of  the  functional  range 
that  may  be  regarded  as  normal,  must  be  considered  greatly  below 
the  highest  scientific  limit.  The  highest  as  well  as  the  lowest  de- 
mands of  the  different  professions  upon  the  central  acuity  differ 
greatly  and  we  have  no  proper  standard  for  their  exact  numerical 
estimation. 

Groenouw  has  proposed  that  it  would  be  suitable  to  gather  exact 
observations  concerning  the  minimum  of  visual  acuity  sufficient  for 
a  certain  vocation  by  examining  the  vision  of  workingmen  in  differ- 
ent factories  and  comparing  the  same  with  the  work  done  on  the 
wages  earned.  We  would  certainly  gain  a  knowledge  of  what 
functional  qualification  may  be  necessary  in  a  certain  trade,  but 
we  do  not  believe  that  we  can  gain  an  exact  knowledge  of  the  lowest 
demands  of  the  different  professions  upon  the  ocular  functions,  as 
we  can  only  find  out  by  such  examinations  the  case  which  has  the 
lowest  vision  and  how  high  is  the  earning  value  of  this  vision.  So 
that,  if  among  the  personnel  of  a  certain  trade  one  workman  with 
a  visual  acuity  of  ^/^  has  been  al)le  to  earn  a  living,  it  may  be  possi- 
ble that  in  the  workmen  of  another  factory  a  still  lower  acuity  of 
vision,  even  ^ ,  may  have  allowed  a  certain  individual  to  earn  a 
living.  But.  if  by  exhausting  the  complete  examinations  of  large 
numbers,  we  have  eliminated  the  probability  of  finding  lower  values, 
even  this  might  not  preclude  the  possibility  of  finding  the  very  low^ 
est  degree  of  vision  which  is  sufficient  for  this  particular  trade. 


ECONOMIC  LIMITATIONS  OF  VISUAL  ACUITY.  35 


kind  of  work  the  individual  may  follow-.  In  the  case  of  a  day 
laborer  whose  visual  functions  are  not  much  taxed  in  his  work,  the 
sudden  reduction  of  whose  vision  to  lo  the  normal  would  probably 
not  prevent  his  working,  but  if  the  vision  of  a  skilled  mechanic 
should  suddenly  be  reduced  to  1/2,  he  will  certainly  have  to  stop,  as 
lie  is  used  to  work  with  clear  retinal  impressions.  In  acknowledg- 
ment of  these  conditions,  the  courts  have  lately  given  opinions  in 
which  the  demands  of  the  particular  professions  have  been  consid- 
•ered.  The  German  Imperial  Insurance  office  (3,  p.  250)  seems  to 
favor  such  principles. 

Considering  the  above,  it  is  advisable  to  give  movable  boundaries  to 
the  economic  limitations  of  vision.  Letus  accept  the  maximum  limits 
as  between  •%  and  3^  of  the  normal  scientific  standard  for  the  visual 
acuit}'  and  in  the  following  our  estimations  will  be  made  with  these 
two  values.  The  loAvest  professional  limit  of  visual  acuity  is  not  in 
concurrence  with  the  minimum  scientific  limit,  for  when  the  acuity 
of  vision  sufficient  for  working  purposes  has  ended,  there  still  re- 
mains an  acuity  that  may  be  judged  by  the  scientific  standard. 
Zehender's  proposition  (53,  p.  268),  where  he  considers  the  lowest 
limit  value  of  the  professional  acuity  as  Moo  of  the  normal  scien- 
tific value  of  vision,  cannot  be  supported.  Professional  work  is 
impossible  with  only  Moo  of  the  normal  visual  acuity.  "We  would 
regard  even  a  far  higher  degree  of  acuity  as  too  low  and  believe  that 
a  standard  for  complete  inability  to  earn  should  be  fixed  at  Mo 
•of  the  normal  visual  acuity.  In  many  cases  even  this  limit  of  Mo 
would  be  too  low,  because  there  are  vocations  in  which  a  higher 
limit  than  V20  would  be  insufficient.  Silex  (39  separate  edition, 
p.  6)  thinks  that  in  certain  branches  of  the  railroad  serAice  and  in 
•certain  other  trades  or  professions  a  visual  acuity  below  Ve  would 
be  insufficient.  It  is,  therefore,  advisable  to  make  the  lowest  eco- 
nomic limit  of  visual  acuity  a  movable  one  and  not  to  fix  an  un- 
changeable value.  We  therefore  adopt  for  the  lowest  economic 
limit  of  the  visual  acuity  two  values,  0.05  (  Mo)  and  the  standard 
of  Silex,  0.15  (about  M  or  M  of  the  normal  visual  acuity). 

Out  of  these  four  limit  values  the  two  maximums  (0.75  and 
0.5)  and  the  two  minimums  (0.15  and  0.05),  we  may  construct  two 
ranges  within  which  the  professional  or  economic  limits  may  lie. 
One  of  these  spheres  or  ranges  would  have  as  its  highest  limit  0.75 
(Mi),  as  the  lowest  0.15  (about  Mr),  while  the  other  range  would 
be  between  0.5  ( M )  and  0.05  ( Mo)  of  the  normal  scientific  stan- 
dard for  visual  acuity.  It  is  not  necessary  that  the  said  maximum 
and  minimum  limit  values  exist  in  both  eyes;  it  is  sufficient  that 
they  be  shown  in  one  eye,  the  other  having  a  lesser  acuity  than  that 
which  we  have  declared  as  absolutely  necessary  for  professional 
optic  demands.  We  believe  that  if  the  second  eye  in  trades  having 
higher  visual  demands,  retains  an  accuracy  of  vision  of  M ,  and  in 
those  having  lesser  demands,  M  •  we  may  speak,  in  a  professional 
sense,  of  "sufficient  visual  acuitv."' 


36  ECONOMIC   LIMITATIONS    OF    VISUAL   ACUITY. 


The  least  acuity  of  Adsion  found  would  only  demonstrate  with  what 
small  degree  oi  vision  an  individual  could  learn  a  trade  or  by  long 
practice  be  able  to  follow  it,  but  it  could  not  show  how  low  the 
visual  acuity  of  a  former  normal  person  might  suddenly  depreciate 
without  making  him  unfit  for  his  trade.  Any  one  entering  a  pro- 
fession while  young  with  a  certain  amount  of  defective  vision  may 
gain  by  practice  full  earning  powers.  The  highly  characteristic 
examples  given  by  Groenouw  (11)  show  how  much  weakness  of 
vision  acquired  in  youth  may  exist  without  marring  the  earning 
capacity. 

There  is  quite  a  difEerence,  hoAvever,  in  the  case  of  a  person, 
starting  to  learn  a  trade,  having  congenital  \X)ov  sight  or  acquiring 
it  in  earl}'  youth,  and  therefore  used  to  indistinct  pictures  on  the 
retina,  and  a  case  of  a  man  with  normal  vision,  accustomed  to  Avork 
with  clear  retinal  pictures,  who,  after  an  accident,  may  have  to 
suddenh'  depend  upon  indistinct  visual  impressions.  The  same 
degree  of  vision  sufficient  in  the  former  case  Avould  not  be  enough 
for  the  latter.  It  is,  of  course,  possible  that  in  the  latter  case,^ 
long  continued  practice  might  finally  lead  to  sufficient  recovery  of 
the  earning  ability  and  the  degree  of  visual  acuity  here  existent 
might  be  considered  as  the  least  compatable  Avith  the  profession. 
But  such  a  rule  could  not  be  made  general.  For  the  recovery  of  a 
certain  degree  of  the  earning  ability  after  diminution  of  the  visual 
acuity  is  not  dependent  u]X>n  the  Avill  of  the  individual,  but  upon 
other  decisiA-e  factors.  The  age  of  the  individual  plays  an  im- 
portant role  in  this  ultimate  comi>ensation.  A  younger  man  may 
easily  OA-crcome  a  high  degree  of  disturbed  vision  and  by  practice 
rec-over  the  lost  earning  poAver;  but  in  an  older  individual  even  a 
lesser  degree  of  visual  disturbance  AA'ill  never  be  overcome.  Any 
intellectually  gifted  individual  AA'ill  be  able  to  make  use  of  indis- 
tinct retinal  impressions  in  his  work  to  a  far  greater  extent  than 
an  intellectually  dull  one.  The  above  factors  shoAv  that  a  certain 
degree  of  visual  acuity  Avould  be  sufficient  in  one  person  for  a  cer- 
tain vocation,  AA'hile  another  could  not  Avork  by  it. 

Although  exact  figures  as  to  the  limits  of  the  Avorking  acuity 
cannot  be  found  by  examination  of  patients,  yet  certain  estimafions 
may  be  made  from  experience.  Josten  (19b,  p.  528)  refers  to  the 
A'isual  limits  acceptable  for  military  service.  The  instructions  for 
military  service  (8,  p.  96)  designate  a  diminished  visual  acuity  to 
^2  of  the  normal  as,  "a  small  disalulity  which  does  not  destroy 
the  general  fitness."  A  Ansual  acuity  in  both  eyes  that  is  betAveen 
/^  and  M  1^5  called  "conditional";  and  if  it  is  Vi  or  below,  it  i& 
called  "absolute  unfitness."  Josten  (19  b,  p.  528)  adopts  the  mili- 
tary standard  to  business  life  as  folloAvs :  "Diminution  of  the 
earning  ability  does  not  take  place  if  there  is  3^  the  normal  visual 
acuity  in  both  eyes."  But,  although  this  proposition  of  Josten  is 
very  simple  and  acceptable,  yet  in  certain  cases  a  shifting  of  the 
visual  standard  above  3^  is  necessary.     This   depends  upon  the 


TABLE  OF  TRADES  SHOWING  VISUAL  DEMANDS.  37 


According  to  this  standard  we  submit  tables  which  divide  the 
followers  of  the  different  manufacturing  vocations  into  two  groups : 

TABLE    A. 

THE    VARIOUS    TPxADES    AND    PROFESSIONS    ARRANGED    ACCORDING    TO 
THEIR  VISUAL  DEMANDS. 

GROUP  I. 

Trades  requiring  liigher  degrees  of  visual  acuity.     Range  0.75  to 
0.15  (scientific  standard). 

The  higher  professions. 

Medicine. 

Theology, 

Law. 

Art. 

Engineering. 

Students   of   all   professions. 

Fine  mechanics. 

Iron  and  steel  workers. 

Eolling  mill  workers. 

Machinists  and  metal  workers. 

Precious  metal  workers. 

Musical  instrument  makers. 

The  linen  industry. 

The  textile  industry. 

The  silk  industry. 

Paper  workers. 

Leather  workers. 

Garment  makers. 

Printers. 

Marine  employees. 

Railway  and  steamship  employees   (including  city  roads). 

Soldiers   and  sailors. 

Telegraph  operators. 

Skilled  labor  generall}^ 

GROUP  11. 

Trades  requiring  lower  degrees  of  visual  acuiig.     Range  0.50  to 
0.05   (scientific  standard). 

Glass  blowers. 

Mine  workers. 

Quarry  men. 

Builders. 

Pottery  makers. 

Brick  makers. 

Workers  in  mechanical  industries. 

Employees  in  gas  and  water  works. 


38  DIFFERENT' VISUAL  DEMANDS  IN  TRADES. 


Paper  makers. 

Wood  workers. 

Mill  empIoA'ces. 

Manufacturers  of  food  articles. 

Sugar  factory  employes. 

Brewers  and  maltsters. 

Tobacco  workers. 

Chimney  sweeps. 

Street  railway  employees  (horse  cars). 

Employees  of  elevators  and  Avine  cellars. 

Teamsters. 

Bargemen  on  inland  waters   (rivers,  etc.). 

Farmers,  etc. 

Day  laborers,  etc. 

Unskilled  labor  generally. 

Individual  members  of  certain  trades  do  not  have  exactly  the 
same  visual  demands  made  upon  them;  some  under  certain  cir- 
cumstances may  have  much  higher  and  others  lower  visual 
requirements.  In  the  course  of  our  work,  in  certain  cases, 
we  must  remember  this  fact  and  not  judge  all  the  members  of  the 
some  trade  by  the  same  standard.  The  railroad  employees  have 
been  officially  divided  into  fixed  classes,  and  if  the  other  trades 
could  be  so  treated,  the  physician  would  know  exactly  into  what 
class  he  should  put  the  individual  case.  We  do  not  desire  to  force 
our  propositions  upon  the  associations,  physicians  or  officials.  .  We 
desire,  however,  that  the  foregoing  shall  be  considered  before  gen- 
erally adopted  principles  be  introduced  into  practice.  It  is  cer- 
tainly advisable  to  reach  some  definite  agreement  as  soon  as  possi- 
ble, as  liitherto  there  has  been  a  disposition  among  oculists  to 
consider  only  the  results  of  the  scientific  examination  of  the  visual 
acuity  as  the  basis  for  the  valuation  of  the  conditions  arising  in 
practical  life.  If  the  estimation  of  the  result  of  the  amount  of 
damage  arising  from  ocular  injuries  is  to  be  made  in  a  just  man- 
ner according  to  actual  conditions,  this  custom  must  be  abandoned. 

Our  views  regarding  the  difference  between  the  scientific  and 
working  standards  of  visual  acuity  can  claim  far  more  extensive 
practical  consideration  than  that  which  relates  alone  to  the  sub- 
ject in  hand  of  ocular  injuries  (Chapter  XIX).  All  profes- 
sions or  vocations  which  make  admission  dependent  upon  a  certain 
degree  of  vision  would  do  well  to  remember  that  practical  visual 
acuity  and  that  of  scientific  standard  are  entirely  different  things 
and  that  an  individual  may  have,  for  working  purposes,  a  full 
amount  of  vision  who  by  the  scientific  standard  shows  a  deficit. 
This  fact  has  been  ignored  in  the  past,  it  being  considered  that  an 
individual  with  defective  visual  acuity  according  to  the  scientific 
standard  must  have  the  same  defect  in  his  working  life.  Individu- 
als have  been  refused  admittance  to  trades  on  ocular  grounds,  al- 


CLASSIFICATION  OF  RAILROAD   EMPLOYEES.  39 


though  if  their  vision  had  been  measured  according  to  the  economic 
and  not  by  the  scientific  standard,  they  could  have  pursued  their 
vocations.  The  authors  have  many  times  seen  how  much  at  vari- 
ance the  purely  scientific  examination  of  the  visual  acuity  could 
be  with  the  demands  made  by  practical  work.  The  management 
of  the  German  roads  have  lately  taken  this  into  consideration,. 
Magnus'  suggestions  having  been  accepted  since  January  1,  1893,  in 
the  Breslau  Eailroad  Company  as  regards  the  qualifications  of 
railroad  employees.  Their  requirements  do  not  now  include  "nor- 
mal" acuity  of  vision  by  the  ''scientific  standard,"  but  only  "suffi- 
cient visual  acuity/'  the  authorities  having  thus  acknowledged  that 
an  estimation  of  the  vision  required  in  railroad  employes  should 
be  made  by  the  practical  economic  or  professional  standard  rather 
than  that  of  the  scientific.  Schmoeckel  (36)  and  Silex  (39)  have 
lately  divided  the  employees  of  railways  into  two  classes  similar  to 
our  proposition.  In  these,  one  eye  is  to  have  at  least  -^^  (Schmoec- 
kel) or  ^  (Silex)  and  the  other  /4  ;  and  in  the  other  class  one 
eye  must  have  at  least  ^  (Schmoeckel)  or  3^2  (Silex)  and  the- 
other  3^  or  3^  of  the  normal  visual  acuity.  Schmoeckel  thus 
divides  the  different  branches  of  railway  employes  according  to  the 
visual  demands  made  upon  them,  into  the  following  groups : 

Group  I. — Without  glasses  on  one  eye  at  least  a  visual  acuity 
of  5^  ,  on  the  other  l^  of  the  scientific  standard :  Locomotive  em- 
ployees (engineers  and  firemen),  station  employees,  switchmen,, 
flagmen,  yardmen. 

Group  II. — With  or  without  glasses  on  one  eye  at  least  a  visual 
acuity  of  3^  and  on  the  other  3^3  of  the  scientific  standard: 
Wipers,  wagonmasters,  brakemen,  guards,  conductors,  baggage- 
masters,  warehousekeepers,  freightmasters,  porters,  watchmen,  des- 
patchers,  roadmasters. 

The  two  groups  proposed  by  Silex  contain  about  the  same  di- 
visions, only  he  puts  brakemen  into  Group  I.,  whereas  they  are  put 
into  the  second  group  by  Schmoeckel. 

In  America  the  tendency  is  to  demand  the  highest  visual  quali- 
fications from  prospective  railway  employes,  the  full  scientific  stan- 
dard of  -%x  (1-0)  being  required  by  many  railroads  and  being 
demanded  as  essential  by  the  consulting  oculists  of  the  principal 
systems.  It  must,  however,  be  observed  that  what  we  call  normal 
visual  acuity  is  a  very  relative  term,  so  that  ^%x,  the  usual 
standard,  may  in  a  good  light  be  read  by  a  young  person  with  re- 
duced visual  acuity,  when  his  real  economic  standard  is  -%v  ,  or 
2%    (Thomson  45,  p.  349). 

Allport  (1)  recently  inquired  into  the  conditions  existent  in 
the  United  States  relative  to  the  vision  required  of  railroad  em- 
ployes, and  in  response  t«  a  circular  letter  received  specific  answers 


40        VISUAL  RAILROAD  REQUIREMENTS  IX  THE  UNITED  STATES 


from  64  railroads  operating  90,950  miles  of  road;  there  being  244 
prominent  railroad  companies  in  the  United  States  which  cover 
205,638  miles  of  road.  Fifty-three  out  of  64  roads  exacted  systematic 
eye  and  ear  examinations,  about  50  per  cent,  requiring  such  examina- 
tions of  all  men  directly  engaged  in  moving  and  operating  trains, 
in  giving  and  receiving  signals,  such  as  engineers,  firemen,  con- 
ductors, brakemen,  j^ardmen.  signalmen,  switchmen,  etc.  This 
examination  is  made  by  a  railway  employee,  such  as  the  superin- 
tendent, trainmaster,  etc.,  and  doubtful  cases  are  sent  to  the  eye 
and  ear  surgeon.  Nine  roads  have  a  regularly  employed  oculist. 
In  three  the  men  are  examined  by  the  railway  surgeon,  and  doubt- 
ful cases  are  referred  to  an  oculist.  In  three  the  examinations  are 
made  by  surgeons  of  Railway  Eelief  Associations.  The  standard  re- 
quired is  various.  In  23  it  is  claimed  that  "perfect  eyes"  are  re- 
quired of  both  old  and  new  employees.  In  16  perfection  is  required 
in  new  men  and  reasonable  concessions  made  to  old  employees.  In 
one  road  engineers  and  firemen  must  possess  of  ^^x  in  one  eye 
and  2^xx  in  the  other;  conductors,  flagmen,  brakemen,  switch- 
men, must  have  a  vision  of  -%xx  in  one  eye  and  ^y^-L  in  the 
other;  all  others  must  have  ^o^^^  in  both  eyes.  One  road  demands 
75  per  cent,  of  the  normal  function,  etc.  This  shows  that  the' 
scientific  standards  required  are  decidedly  different.  We  are,  how- 
ever, fast  coming  to  the  conclusion  that  a  practically  perfect  U'ork- 
ing  or  economic  standard  of  visioti  should  be  required  for  new  men 
and  that  they  should  not  have  any  grade  of  refractive  error,  such 
as  hyperopia  over  2.5  D,  which  would  ultimately  render  their 
distant  vision  poor,  as  owing  to  the  dust  and  exposure  of  railway 
service,  the  vision  should  be  normal  without  the  correction  of  any 
refractive  error  by  glasses. 

Allport  (1)  divides  the  railway  employees  into  two  classes  ac- 
cording to  their  specific  vocations. 

Class  A. — In  which  the  vision  is  required  to  be  at  least  ^%xx 
in  one  eye  and  ^^l  in  the  other,  and  which  must  be  reached 
without  glasses;  distance  glasses  are  not  allowed  on  duty. 

Class  B. — In  which  the  vision  shall  be  at  least  ^/^l  in  one 
eye  and  20^  in  the  other,  and  in  which  the  employee  is  not  only 
allowed  to  wear  glasses,  but  is  required  to  do  so  if  the  refractive 
error  is  such  that  it  is  necessary  to  bring  vision  up  to  the  proper 
standard- 

Class  A. — Engineers,  firemen,  conductors,  brakemen,  switch- 
men, signalmen,  switch-tenders  and  engine-dispatchers. 

Class  B. — Track  foremen,  bridge  foremen,  crossing  flagmen, 
bridge  tenders,  gatemen,  train  baggagemen,  telegraph  operators, 
station  agents  and  station  baggagemen. 

Williams  (48)  makes  about  the  same  subdivision  of  the  classes 
and  demands  the  following;: 


ADVISABILITY  OF  GEXERAL  AGREEMENT  FOR  VISUAL  REQUIREMENTS. 41 


Class  A. — Engineers,  firemen.  For  entrance  to  the  service  or 
promotion,  ^^x  or  average  normal  vision  in  each  eye,  re-exam- 
ination every  three  years  not  less  than  ^%xx  '"'ith  both  eyes 
open  without  glasses. 

Class  B. — For  entrance  to  the  service  or  promotion  -/^x  in 
one  eye  and  not  less  than  ^/^l  in  the  other  and  for  re-examina- 
tion every  three  years  not  less  than  ^^^l  with  both  eyes  open  with- 
out glasses. 

Thus  in  Germany  the  application  of  the  full  scientific  stan- 
dard to  the  eases  of  railway  employees  has  been  abandoned  and 
visual  acuity  of  ^  or  ^  is  regarded  as  sufficiently  high,  and, 
therefore,  we  may  consider  this  quantity  as  the  normal  economic 
standard  or  1.0.  As  these  considerations  will  be  ultimately  ac- 
cepted, it  is  perhaps  advisable  to  adapt  our  test  letters  to  the  pro- 
fessional standard.  This  may  be  easily  done  on  the  examination 
cards  now  in  use,  if  we  would  mark  the  lines  on  Jager's  types  or 
Snellen's  cards  (see  Plates  II.,  III.),  which  are  equivalent  to  ^ 
or  ^  of  the  scientific  standard  as  the  full  professional  acuity  for 
the  higher  trades  and  ^  or  ^  that  for  trades  demanding  less 
visual  acuity.  The  German  Ministry  of  Railroads  (38)  has  lately 
divided  its  employees  into  dilferent  classes  as  regards  their  visual 
demands  and  has  therewith  given  the  examining  physician  a  basis 
for  judgment  of  the  ocular  earning  ability  in  the  individual  case. 
It  would  be  desirable  that  the  Accident  Insurance  Companies  and 
Railroads  of  America  and  the  managements  of  other  vocations  de- 
manding specific  visual  qualifications,  would  do  the  same  thing  with 
all  applicants. 

When  we  have  thus  placed  the  meaning  of  economic  visual 
acuity  within  materially  narrower  limits  than  that  which  the  sci- 
ence of  ophthalmology  permits,  we  must  not  forget  that  our  charts 
used  for  estimation  of  the  visual  acuity  correspond  only  with  the 
scientific  standard.  Thus  in  each  case  the  remaining  degree  of 
visual  acuity  according  to  the  scientific  standard  found  by  the 
physician  in  the  case  of  the  injured  person  should  be  transposed 
into  that  of  the  economic  standard  before  it  may  be  used  for  esti- 
mating the  damage  to  the  earning  ability.  This  is  done  in  the 
following  table : 


42 


CONVERSIOX  OF  VISUAL  STANDARDS. 


TABLE    B. 

THE    SCIENTIFIC    STANDARD    FOR    VISUAL    ACUITY    CONVERTED    INTO 
ECONOMIC    TERMS. 


II. 


Scientjtic 
standard. 

Econoniif 
vocations 

standard  for 
demanding 

Scientifle 
standard. 

Kconodiir 
vocations 

standard  for 
demanding 

lii^he 

-  degrees. 

lesse 

-  de^^rees. 

0.75  = 

1 

0.50 

= 

1 

0.70  = 

0,9166.. 

= 

^Mo 

0.45 

= 

0.8888.. 

=        ^ 

0.65  = 

0,8333.. 

= 

'%2 

0.40 

= 

0.7777.. 

=       V9 

0.60  = 

0,750  .. 

== 

M2 

0.35 

= 

0.6666.. 

=    Y^ 

0.55  = 

0,6666.. 

= 

yi2 

0.30 

= 

0.5555.. 

=    V^ 

0.50  = 

0,5833... 

= 

M2 

0.25 

= 

0.4444.. 

=  y^ 

0.45  = 

0,500  ... 

= 

/12 

0.20 

= 

0.3333.. 

=  H 

0.40  = 

0,4166... 

= 

yi2 

0.15 

= 

0.2222.. 

=  ^ 

0.35  = 

0,3333... 

= 

yi2 

0.10 

= 

0.1111.. 

=  H 

0.30  = 

0,250  ... 

= 

M2 

0.05 

= 

0.000 

0.25  == 

0,1666... 

= 

M2 

0.20  = 

0,0833... 

= 

M2 

0.15  = 

0,000 

In  tables  which  follow,  by  which  the  state  of  the  earning 
ability  in  cases  of  different  ocular  injuries  is  estimated,  the  calcu- 
lation is  always  based  upon  the  values  altered  as  above,  but 
as  this  valuation  is  not  yet  generally  accepted  and  the  fixing 
of  the  acuity  of  vision  is  generally  done  according  to  the  method 
of  Snellen,  we  have  also  given  the  degrees  according  to  scien- 
tific standard.  It  must  be  remembered  that  in  all  our  tables  the 
amounts  of  visual  acuity  correspond  with  the  scientific  values 
transformed  as  above  into  the  professional  ones.  Thus  with  visual 
acuity  of  0.4,  its  economic  value  is  not  0.40  but  0.7777  .  .  ,  if  the 
injured  person  has  a  profession  with  slight  visual  demands;  but 
if  it  requires  a  higher  degree  of  vision,  the  scientific  standard 
of  visual  acuity,  0.4,  would  be  transformed  into  0.4166  .  .  ,  with 
which  the  calculation  is  made. 

We  show,  figuratively,  the  relations  between  the  scientific  and 
the  economic  visual  acuities  in  Plate  I.  (Frontispiece).  In  this 
drawing  the  degrees  of  vision  in  the  absciss  and  the  ordinate  axis 
are  marked,  at  intervals  of  0.01, so  that  five  of  these  are  always  taken 
together;  the  absciss  as  well  as  the  ordinate  axis  are  divided  by  this 
into  20  equal  parts.  The  curve  of  the  scientific  visual  acuity  is 
marked  as  a  coarse  black  line  d)  and  because  this  progresses  gradu- 
ally, it  has  been  equally  divided.  Economic  vision  will  not  suffer 
very  much  if  the  acuity  falls  off  0.05,  because  the  difference 
between  1  and  0.95  is  so  little  that  it  will  scarcely  be  noticed.  But, 
if  the  acuity  falls  off  further,  a  point  will  soon  be  reached  where 


ECONOMIC  LIMITS  OF  VISUAL  FIELD.  43 


every  loss  affects  the  working  capacitj'^,  and  if  the  vision  falls  be- 
low this  point,  for  instance,  to  0.005,  tlien  it  has  no  economic  value 
whatever,  and  when  it  reaches  this  lowest  point  and  further  de- 
preciates, vision  will  be  professionally  of  no  importance.  Corres- 
ponding with  these  facts,  the  two  curves  of  the  economic  visual 
acuities  should  not  be  marked  as  grades ;  the  beginning  and  end  of 
the  curves  should  deviate,  as  we  have  shown,  but  these  deviations 
are  so  little  that  we  have  divided  them  similarly  to  that  of  the  scien- 
tific standard.  The  fine  line  (II)  shows  the  course  of  economic 
vision  for  higher,  and  the  broken  (III)  line  for  trades  having  lesser 
visual  demands.  As  the  drawing  shows,  both  curves  start  together 
with  the  absciss-axis,  and  then  when  the  climax  of  the  demands  is 
reached,  they  run  parallel. 

We  have  also  evolved  test  types  corresponding  to  those  of 
Jager  for  proximal  vision  and  to  Snellen's  for  distant  vision  (see 
Plates  II  and  III).  The  ordinary  Snellen  test  cards  may  be  used 
in  the  same  way  by  reducing  the  scientific  standards  to  economic 
terms. 

§13.     The  Economic  Limits  of  the  Visual  Field  and  their  Estima- 
tion. 

The  limits  of  peripheric  vision  are  to  be  regarded  from  either 
a  scientific  or  an  economic  standpoint,  and  as  has  been  shown  in 
discussing  the  visual  acuity  are  quite  different.  Peripheric  limita- 
tions or  even  greater  defects  of  the  field  of  vision,  if  only  in  one 
eye,  and  under  certain  circumstances,  a  moderate  limitation  of  the 
visual  fields  of  both  eyes,  will  not  impair  their  earning  capacity.  We 
would  only  regard  limitation  of  the  field  of  vision  as  entitled  to 
an  indemnification,  if  the  limits  for  white  in  the  binocular  field  are 
temporal  70°,  superior  40°,  inferior  60° ;  and  in  the  monocular 
type,  temporal  70°,  nasal  45°,  superior  40°,  inferior  65°.  This 
corresponds  to  those  limitations  which  Haab  (15,  Table  I.,  figure 
la)  adopts  as  the  narrowest  ones  admissible  under  normal  condi- 
tions. The  suggestion  of  Schroeter  (37,  p.  16)  is  very  useful  in 
estimating  the  amount  of  economic  damage  to  the  field  of  vision. 
Therefore,  like  Schroeter,  we  divide  the  binocular  field  into  three 
zones  of  30°  each:  the  first  from  the  outermost  periphery  to  60°, 
the  second  from  60°  to  30°,  and  the  third  from  30°  to  the  point  of 
fixation  (Plate  IV.,  figure  1).  It  is  evident  that  these  three  zones 
do  not  have  the  same  value  functionally;  the  inner  one  has  the 
most,  the  outer  the  least,  but  nevertheless  as  it  complicates  the 
subject  too  much  we  do  not  give  them  a  different  value  like 
Schroeter  does.  We  are  of  the  opinion  that  the  functional  differ- 
ences of  these  zones  can  hardly  render  itself  felt  economically,  for 
the  outermost  zone  of  the  field  of  vision  represents  a  much  greater 
range  of  the  retina  than  the  central,  and  the  intermediate  one 
represents  a  greater  range  than  the  inner  one.  But  what  the  outer 
zone  lacks  in  functional  ability  compared  with  the  two  others,  it 


44  ECONOMIC  LIMITS  OF  MUSCLES. 


makes  up  by  its  greater  extent,  so  that  for  practical  use  the  ex- 
tent of  the  different  zones  is  compensated  for  by  the  relative  differ- 
ence in  the  functional  ability;  therefore  we  give  each  of  these 
zones  the  same  value.  The  entire  binocular  field  of  vision  P,  would 
be  composed  of  three  factors  of  equal  value.  According  to  this  all 
defects  of  the  field  of  vision  could  be  given  their  numerical  valua- 
tion, for  instance,  with  the  loss  of  one  eye  we  would  lose  I/q  of  the 
binocular  field,  with  a  homonymous  hemianopsia  f^e,  etc.  In 
paragraph  11  we  have  noted  the  reasons  for  introducing  the  visual 
field  as  a  root  value  into  the  formula  for  the  visual  act. 

§14.     The   Economic  Relations   of   the   Ocular   Musculature   and 
their  Estimation. 

The  outer  ocular  muscles  have  their  peculiar  relations  to  the 
earning  power.  In  view  of  the  fact  that  the  binocular  act  of 
vision  in  its  earning  relations  may  only  be  regarded  as  preserved  if 
all  the  ocular  muscles  be  unimpaired,  the  functional  disturbance  of 
one  single  ocular  muscle  is  a  bad  one,  because  with  the  paralysis  of 
one  muscle  diplopia  appears  and  immediately  suspends  the  binocu- 
lar act,  causing  thereby  complete  exclusion  of  the  affected  eye. 
Therefore,  if  both  eyes  are  functional  and  the  act  of  vision  was 
binocular,  a  paralysis  of  one  ocular  muscle  should  be  regarded 
from  an  economic  standpoint  in  the  same  light  as  the  complete 
loss  of  one  eye,  and  the  diminution  of  the  earning  ability 
must  be  the  same  as  the  loss  of  one  eye,  even  if  it 
be  only  temporary.  Less  consideration  should  be  claimed 
for  the  loss  of  the  function  of  one  ocular  muscle  if  the 
act  were  previously  monocular.  In  such  a  case  the  loss  of  one 
muscle  is  only- an  inconvenience  or  may  be  termed  a  small  injury. 
We  regard  the  action  of  the  outer  ocular  musculature  as  a  sum  of 
different  muscular  actions,  corresponding  with  the  number  of  the 
outer  muscles,  which  makes  a  sum  of  six  individual  functions. 
By  omitting  one  muscle,  the  muscular  action  will  appear  in  the 
formula  for  the  act  of  vision  as  a  fraction,  ^ .  The  fact  that  the 
six  outer  muscles  of  the  63^6  are  not  of  the  same  relative  value  for 
the  earning  capacity  has  also  to  be  considered.  Quite  different 
demands  are  made  by  certain  vocations ;  for  instance,  in  the  case 
of  miners,  the  rectus  superior  is  particularly  needed  (N'ieden  31), 
while  in  other  trades  it  is  but  little  used.  In  all  factors  demanding 
clear  vision  in  the  distance,  as  that  of  sailors,  the  rectus  externus 
is  more  used  than  in  those  professions  whose  work  is  near  the  eye ; 
in  the  latter  the  rectus  internus  is  the  most  prominent  muscle  and 
for  general  use  we  think  that  the  internal  rectus  should  be  given 
the  most  prominent  place  as  regards  the  earning  capacity.  This 
varying  value  of  the  outer  ocular  muscles  in  the  difPerent  pro''es=ions 
makes  the  valuation  somewhat  difficult;  for,  if  we  gauge  the  mus- 
cles by  the  standard  put  for  one  certain  vocation,  we  would  make  a 


THE  INTRINSIC  MUSCLES.  45 


mistake.  For  instance,  if  we  give  the  valuation  to  the  rectus 
superior  that  is  needed  in  the  case  of  a  miner,  it  would  be  over- 
valuation f oi'  most  of  the  other  professions  and  an  under-valuation 
of  the  other  muscles.  It  is,  therefore,  for  ordinary  purposes,  neces- 
sary to  regard  the  outer  ocular  muscles  as  of  equal  value  and  to 
give  each  ^  of  the  total.  But  in  special  cases  we  can  do  justice  to 
the  demands  of  the  different  professions  and  when  necessary  value 
them  higher,  for  instance,  5^  or  /^  .  We  have  deemed  it  necessary 
to  introduce  the  muscular  action  as  a  root  value  m  the  full  formula 
for  the  act  of  vision  (§  11,  p.  30.) 

In  only  exceptional  cases  could  injuries  of  the  intrinsic  muscles 
(affecting  the  accommodation  or  the  pupil)  have  any  special  in- 
fluence upon  the  earning  ability,  because,  by  the  use  of  suitable 
convex  glasses,  the  derangement  may  be  overcome. 


46  THE  ABILITY  TO  COMPETE. 


CHAPTER  Vn. 


§15.     The  Meaning  and  Estimation  of  the  Ability  to  Compete. 
(K  of  our  formula  for  the  earning  ability.) 

As  we  have  explained  in  Chapter  IV.  the  ability  to  compete  is 
one  of  the  three  factors  composing  the  full  earning  ability.  We 
have  shown  that  this  is  the  least  valuable  of  the  three  and  that  it 
should  be  inserted  into  the  formula  with  a  smaller  value  than  the 
other  factors.  We  will  make  a  few  remarks  regarding  the  position 
this  factor  takes  in  the  estimation  of  the  injury  to  the  ocular  earn- 
ing ability. 

When  an  individual  receives  an  accidental  injury,  especially 
that  of  vision,  the  damage  to  him  is  a  double  one.  First,  there  is 
the  impairment  of  his  working  ability  from  the  results  of  the  acci- 
dent in  that  he  cannot  perform  as  good  or  as  much  work  as  for- 
merly, and  second  his  chances  for  obtaining  work  quickly  and 
easily  are  less.  This  second  factor  is  not  so  unessential  as  one 
might  suppose.  Practical  experience  shows  that  the  one-eyed  per- 
son not  only  has  more  difficulty  in  finding  employment,  but  that 
in  some  factories  his  visual  disorder  makes  it  difficult  for  him  to 
retain  his  employment.  Workmen  with  sound  eyes  are  preferred 
by  most  employers  of  labor  and  from  their  standpoint,  certainly 
not  without  reason.  The  injured  person,  therefore,  has  a  right  to 
claim  not  alone  a  compensation  for  the  impairment  of  his  capacity 
for  work  but  also  the  difficulty  which  he  encounters  in  making  the 
most  of  this  capacity.  Therefore,  in  estimating  the  impairment 
of  the  earning  ability,  we  have  always  and  under  all  circumstances 
to  consider  the  diminution  of  the  ability  to  compete. 

The  ability  to  compete  is  a  conception  resulting  from  a  com- 
bination of  heterogenic  elements  of  which  a  part  lies  in  the  indi- 
vidual himself  and  is  affected  by  the  condition  of  his  health,  his 
knowledge,  etc.,  while  another  portion  is  beyond  his  control.  It  is 
this  latter  element  the  world  values  in  judging  the  ability  of  the 
individual.  The  ability  to  compete  in  the  labor  market,  the  possi- 
bility of  finding  employment,  is  fixed,  therefore,  by  the  physical  and 
mental  ability  of  the  individual  as  well  as  by  the  way  others  judge 
of  it.  If  we  apply  this  reasoning  to  the  organ  of  vision,  the  ability 
to  compete  of  each  individual  will  depend  firstly  upon  the  ability 
of  the  visual  organ  and  secondly  upon  the  way  others  are  judging 
its  condition;  an  example  should  render  this  clear.  Supposing 
some  one  has  suffered  an  injury  to  one  eye  and  seeks  employment, 
his  chances  of  obtaining  the  desired  work  will  depend  first,  upon 
his  visual  powers  and  secondly,  upon  the  way  the  employer  judges 


THE  ABILITY   TO   COMPETE.  47 


them.  The  employer  will  be  willing  to  give  or  refuse  work  to  this 
particular  individual  according  to  how  he  regards  the  injury  of  the 
eye  as  detrimental  for  the  performance  of  Ms  particular  work.  If 
we  desire  to  state  the  ability  as  a  numerical  quantity,  we  must  con- 
sider such  conditions,  which  we  think  we  can  do  by  the  following: 

The  Part  of  tiie  Ability  to  Compete  That  Each  Indi- 
vidual Supplies  by  Himself,  in  our  case  the  ability  of  his  organ 
of  vision,  we  bring  forward  into  the  formula  under  normal  con- 
ditions when  we  insert  the  expression  for  the  normal  act  of  vision, 

1 

C  V  F  V  M,  but  in  the  case  of  accidents  the  impaired  value  of  the 
act  of  vision  should  be  put  in  as  the  lowest  value  in  the  root.  In 
Chap.  IV,  §  9.  we  have  given  the  reasons  for  accepting  the  ability  to 
compete  as  the  lowest  value  and  we  have  likewise  shown  that  the 
ability  to  compete  is  of  less  value  in  the  formula  for  the  earning 
ability  E  than  the  other  factors,  i.  e.,  it  has  a  smaller  influence  upon 
the  value  of  E  than  the  others.  We  have,  therefore,  adopted  the 
ability  to  compete  K  as  a  root  value.  For,  if  K  be  reduced  by  an 
impairing  of  the  act  of  vision,  it  becomes  a  proper  fraction,  for  in- 

K 
stanc^,       .     ISTow  the  root  of  a  proper  fraction  is  always  greater 

Z  .  "  .    . 

than  the  fraction  itself;  the  value  of  K. after  the  impairment  if  it 

\r 

is  taken  as  a  root  vahie  can  not  any  more  l)e         but  it  must  be 

2K  ^ 

greater,  for  instance,  -     .     By  taking  K  as  a  root,  its  value,  in  the 

case  of  a  visual  impairment,  is  greater  than  it  would  have  been  if 
K  without  root  would  have  been  taken  into  the  calculation.  And 
as  the  amount  of  the  earning  ability  is  directly  fixed  by  the 
amount  of  the  ability  to  complete,  K  exercises  less  influence  upon 
the  earning  ability  than  the  other  factors,  as  soon  as  we  insert  K  as 
root  in  the  formula  for  the  earning  ability.     The  full  formula 


being:     f^  =  V  ^^^^^ 

The  Part  of  the  Ability  to  Compete  Not  Depending  Upon 
the  Individual,  in  Our  Case  Not  Upon  the  Condition  of  the 
Eyes,  but  Upon  the  JuDorENT  of  the  Employer,  we  ren- 
der by  the  exponent  of  the  root  which  we  chose  for  K;  taking 

K 
a  small  exponent  the  value  of        will  be  enhanced  to  a  less  extent 

and  if  we  take  a  large  exponent  to  a  higher  extent.  If  we  enhance 
the  value  of  the  ability  to  compete  by  taking  a  greater  root  ex- 
ponent, as  the  earning  ability  increases  as  much  as  the  ability  to 
compete  becomes  greater,  the  earning  ability  will  he.  greater  accord- 
ing to  the  size  of  the  root  exponent.  If  we  would  indicate  that  the 
employer  regards  a  certain  ocular  impairment  as  an  iuiportant  di- 
minishment  of  the  working  cajisicity  we  would  take  a  smaller  ex- 
ponent, but  if  we  intend  to  show  that  an  ocular  impairment  is  of 


48  ELASTICITY  OF  OUR  METHODS. 


less  importance  to  the  employer,  avc  would  take  a  greater  one.  We, 
therefore,  choose  for  all  slight  and  moderate  visual  impairments 
a  different  root  exponent  than  for  tlic  serious  ones;  therefore,  for 
the  slight  impairments  we  give  the  ability  to  compete  the  root  ex- 
ponent 10,  but  if  the  impairment  of  central  vision  is  serious,  i.  e., 
in  the  case  of  professions  with  higher  visual  demands  if  it  falls  be- 
low 0.15  and  in  those  with  less  demands  below  0.05,  and  instead  of 
the  root  exponent  10  we  take  the  exponent  5  for  these  professions 
with  greater  visual  demands  and  the  exponent  7  for  those  with  less. 
The  same  is  to  be  done  in  the  case  of  the  complete  loss  of  one  eye 
or  in  the  case  of  the  loss  of  the  eveball.  If  we  think  that  the  aes- 
thetic dilferences  between  simple  blindness  of  the  scientilic  standard 
without  injury  to  the  looks  of  the  eye  and  the  loss  of  the  eyeball,  or, 
for  instance,  the  formation  of  a  bad  looking  eye,  as  leucoma  or 
staphyloma  are  greater,  we  may  give  expression  to  our  opinion  by 
choosing  a  great  root  exponent  for  the  ability  to  compete  in  the  case 
of  simple  blindness  without  deformity.  By  leaving  the  selection 
of  the  root  exponent  to  the  judgment  of  the  calculator,  sufficient 
room  is  given  for  the  individual  conception  of  each  case;  thus  our 
formula  adapts  itself  to  the  peculiarities  of  the  individual  case  and 
to  the  judgment  of  the  physician,  avoiding  thereby  a  rigid  form  and 
doing  justice  to  both  parties.  Therefore,  in  forming  a  special  esti- 
mation of  the  ability  to  compete  we  first  fix  the  amount  of  the 
injury  to  the  act  of  vision  in  each  case,  and  upon  this  depends  that 
part  of  the  ability  to  compete  which  the  individual  furnishes  him- 
self. As  regards  the  second  part,  in  certain  cases  it  will  be  found 
that  while  there  is  no  or  but  little  actual  injury  to  the  visual  sense 
itself,  yet  certain  injuries  of  the  eye  disturb  the  relations  of  the 
individual  to  the  employer. 

Such  a  case  as  the  following  is  often  experienced  in  practice: 
A  man  has  his  cornea  burned  by  lime  which  leads  to  the  formation 
of  leucoma  and  diminishes  the  visual  acuity  of  that  eye  to  0.25  of 
the  normal,  the  other  eye  remaining  well.  Thus,  although  such  an 
individual  is  not  optically  impaired  for  his  work  because  the  normal 
eye  allows  the  undisturbed  following  of  his  trade,  the  chances  of  his 
finding  work  have  become  less.  A  great  many  employers  would 
hesitate  to  take  into  their  service  a  man  with  a  bad  looking  eye, 
who  shows  so  plainly  the  effects  of  the  injury  or  who,  he  knows, 
can  see  normally  only  with  one  eye;  in  spite  of  the  fact  that  in  such 
a  case  an  actual  impairment  has  not  taken  place  the  ability  to  com- 
pete is  certainly  diminished.  We  are  consequently  in  the  peculiar 
position  of  estimating  an  ocular  impairment  of  the  abilitv  to  com- 
pete when  there  is  no  real  defect  of  working  vision.  Thus  we  think 
we  can  meet  these  difficult  conditions  in  the  best  manner  if  we  ex- 
press the  diminution  of  the  ability  to  compete  in  all  cases  by  the 
arithmetical  proportion  of  the  visual  acuity  of  both  eyes.  The 
ability  to  compete  is  in  fact  a  quantity  which  is  almost  identical 
with  the  act  of  vision  but  not  dependent  upon  it  as  the  maximum 


IMPAIRMENT  OF  ABILITY  TO  COMPETE.  49 


of  the  visual  acuity  in  both  eyes.  In  our  example  we  suppose  that 
the  vision  of  one  eye  remains  normal  while  that  of  the  other  was 
diminished  to  0.25,  consequently  the  numerical  expression  for  the 
ability  to  compete  would  be : 


r 


1  +  0,25 


V  F  V  (mi  ma  m.,  m*  m.^  ms)    (mi"  m/  m/  m/  m/  m/) 


The  reasons  for  expressing  the  impairment  of  the  ability  to 
compete  by  the  arithmetical  proportion  of  the  central  acuities  of 
both  eyes  are  the  following :  Even  if  a  diminishment  of  the  binocular 
acuity  of  vision  cannot  be  proven  scientifically  where  one  eye  is 
alone  affected,  professionally  the  binocular  vision  has  not  the  same 
value  as  formerly.  If  we  unite  the  normal  vision  of  the  one  eye 
and  the  impaired  one  of  the  other  by  the  mathematical  expression 
of  the  arithmetical  proportion,  the  value  of  the  normal  acuity  will 
be  diminished  by  the  size  of  the  injury  to  the  other  eye;  we  then 
use  this  arithmetical  proportion  as  the  root  value  with  the  exponent 
10  and  thus  provide  that  the  normal  vision  is  but  slightly  reduced 
by  the  impairment  of  the  vision  in  the  other  eye.  By  this  means 
the  practical  conditions  may  be  satisfactorily  considered.  If  one 
of  the  other  factors  entering  into  the  economic  act  of  vision  be  im- 
paired, for  instance,  the  peripheric  vision,  while  all  the  other  fac- 
tors as  well  as  the  central  acuity  remain  untouched,  the  impairment 
of  the  factor  in  question  should  be  used  in  such  a  manner  that  we 
first  insert  it  into  the  expression  for  the  normal  act  of  vision  as 
the  tenth  root  in  the  calculation.  For  instance,  from  an  accident 
only  the  field  of  vision  has  suffered  and  if  it  is  only  two-thirds  of 
its  original  range  while  the  central  acuity  and  the  muscles  remain 
imchanged,  we  enter  into  the  formula  for  the  normal  professional 
act  of  vision  for  the  field  of  vision  P  the  value  two-thirds.  The 
formula  for  the  ability  to  compete  would  thus  be: 


y 


ex   K  %  P   K  (mi  m.  m:!  m^  m.^  mfi)   (m/  m./  m/  m/  ms'  m/) 


If  several  of  the  factors  be  damaged  at  the  same  time,  the 
amount  of  such  damage  has  to  be  inserted  into  the  formula  as  the 
xth  root.  For  instance,  the  central  acuity  of  vision  in  both  eyes 
diminishes  to  0.30  (scientific  value),  while  the  field  of  vision  be 
limited  to  one-third,  these  values  for  the  acuity  and  the  field  would 
have  to  be  first  entered  into  the  formula  of  the  working  act  as  an 
arithmetical  proportion,  being  changed  correspondingly  while  the 
numerical  value  of  the  muscular  action  would  remain  the  same,  the 
formula  then  would  be : 


X 

f 


0,30  +  0,30 


2  VV^  P  /  (mi  mo  m:,  m4  m-,  mr.)   (m/  mo'  m/  m/  mr,'  m/) 


50  USE  OF  DIFFERENT  ROOT  EXPONENTS. 


and  if  we  enter  this  below  the  tenth  root,  the  formula  would  be' 
transposed  into : 


y 


0.30  +  0.30 


VV&PV  (mi  ma  ms  m*  m,  me)    (m/  m/  m/  m/  m./  m/) 


If  one  eye  be  entirely  lost,  the  disorder  of  the  visual  act  would 
be  represented,  in  vocations  with  higher  visual  demands,  the  fifth 
root,  and  in  such  with  less  demands  the  seventh  root.  The  same 
calculation  may  be  done  for  serious  disorders  which  have  the  same 
relations  as  the  loss  of  one  eye. 


THE  FORMULA  OF  MAGNUS.  51 

CHAPTER  Vm. 


THE  METHOD  OF  CALCULATION  WITH   THE  FORMULA 
OF  MAGNUS. 


§16.     What  Does  this  Formula  Mean? 

In  Our  Formula  for  the  Ocular  Earning  Ability, E=F/K 

X 

the  visual  act  being  F  and  V'K  the  ability  to  compete,  by  resolving  the 
act  of  vision  F  into  its  physiologic  factors  necessary'  for  the  earning 
ability,  C  is  the  maximal  central  visual  acuity,  P  the  visual  field  and 
M  the  muscular  action  (Chap.  VI.,  §  11-14),  we  had  acquired  the 

expression:  F=C  (max.)  V  P  1^  M    for    the    physiologic    act    wliile 

X 

for  the  ability  to  compete  v'^we  had  (Chap.  VL,  §  11-14)  : 


VY=f^^^'^^V'¥VlL 


The  complete  formula  for  the  ocular  earning  ability  being  the 
following : 


E  =  C  („,ax.)  V  P  V  M    f^'  '^^'V  P  V'  M. 

At  the  first  glance  it  might  seem  that  our  formula  has  too  much 
of  the  mathematical  stamp  and  that  its  handling  does  not  seem 
easy  nor  convenient,  and  it  has  been  called  "too  complicated" 
(Groenouw  12).  But  this  reproach  only  shows  that  those  making 
it  did  not  comprehend  or  understand  its  meaning.  This  formula 
is  the  numerical  expression  for  the  normal  visual  earning  ability, 
and  while  this  is  a  composite  quantity  its  mathematical  expression 
must,  of  course,  be  composite.  This  is  especially  true,  for  each  of 
the  factors  entering  into  the  normal  visual  earning  ability  may  be 
impaired  and  must  have  an  individual  influence  upon  the  calcu- 
lation. If  we  try  to  simplify  the  complicated  relations  they  could 
only  be  forced,  and  an  arbitrary  speculation  substituted  for  its  own 
composite  character.  The  formulas  of  Zehender  and  Groenouw 
are  certainly  not  real  mathematical  expressions  for  the  ocular  earn- 
ing ability,  but  only  mathematical  results  of  arbitrary  supposi- 
tions. By  the  construction  of  such  seemingly  simple  foi-mulas  we 
depart  entirely  from  the  line  of  conduct  nature  itself  follows  and 
get  into  devious  tracks  of  arbitrary  hypotheses.  Our  duty  is  to 
give  expression  to  the  ocular  earning  ability  in   a   mathematical 


52  CONVENIENT  FIGURING  WITH  THE  FORMULA. 


manner  according  to  its  nature,  but  in  doing  this  we  must  not 
create  a  formula  made  easier  to  handle,  but  which  is  nothing  but  an 
arbitrary  conception.  Arithmetical  simplicity  could  only  be  arrived 
at  by  the  waiving  of  the  natural  relations.  While  an  exact  mathe- 
matical rendering  of  these  may  not  be  so  very  convenient,  we  may 
expect  that  results  may  be  gained  which  correspond  with  the  actual 
conditions.  By  doing  so,  such  reductio  ad  ahsurdum  cannot  be 
found,  as  is  the  case  with  the  simple  hypothetic  formulas  of  Zehen- 
der  and  Groenouw.  The  arithmetical  results  of  introducing  human 
beings  with  three  seeing  eyes,  or  nine  eyes,  or  cyclopia,  or  arriving 
at  the  conclusion  that  one-eyedness  is  identical  with  the  entire  loss 
of  the  ocular  earning  ability,  cannot  be  excused  or  made  acceptable 
by  the  arithmetical  simplicity  of  the  formula. 

§17.     Can  Figuring  ivith  the  Fonnula  Be  Made  More  Convenientf 

In  our  last  paragraph  we  had  to  defend  our  formula  from  the 
reproach  of  being  too  complicated,  but,  under  all  circumstances,  it 
is  the  truest  mathematical  expression  of  natural  conditions  and  has 
to  be  made  the  starting  point  for  every  calculation.  We  may,  how- 
ever, try  to  make  it  more  convenient,  as  it  must  be  admitted  that 
the  separate  figuring  of  the  individual  factors  with  the  root  values 
certainly  offers  difficulties  to  the  inexperienced  mathematician  and, 
therefore,  a  way  has  to  be  found  which,  while  retaining  absolutely 
the  formula,  materially  facilitates  and  simplifies  the  calculation. 
This  we  do  as  follows : 

In  plate  V  we  delineate  each  of  the  factors  of  our  formula  in 
a  curve  in  such  a  manner  that  the  individual  curves  give  the  con- 
dition of  this  factor  within  its  working  range.  For  instance,  in 
plate  V,  line  I  shows  the  geometric  course  of  peripheric  vis  "on.  if 
the  scientific  value  of  P  as  absciss  and  the  economic  value  V  P  are 
taken  as  ordinates :  line  II  represents  the  geometric  course  of  the 
muscular  action,  if  the  scientific  value  of  ^I  as  absciss  and  the 
economic  or  actual  value  *V  M  arc  taken  as  ordinates.  The  three 
lines.  III,  TV  and  Y,  show  in  an  analogous  manner  the  ability  to 
compete  in  its  different  values,  using  the  oth,  7th  or  10th  root.  By 
the  assistance  of  these  curves  we  may  ascertain,  in  a  given  case,  the 
economic  value  of  the  impairment  of  every  factor  of  our  formula. 
We  first  ascertain  the  amonnt  of  impairmeut  on  the  absciss  repre- 
senting the  scientific  valuation,  then  we  trace  vertically  the  corre- 
sponding line  from  this  point  on  the  chart,  and  at  the  intersecting 
point  where  we  meet  the  ordinate  on  the  left  of  the. curve,  is  the 
economic  value  of  the  damage.  By  this  method,  the  very  incon- 
venient handling  of  the  root  values  and  separate  figuring  of  the 
single  factors  of  the  formulae  mav  he  avoided.  Thus,  with  any 
great  amount  of  mathematical  calculation,  we  may  estimate  the 
economic  value  of  each  damage  of  the  different  factors  shown  in 
the  tables. 


EXAMPLE,  VISION  IMPAIRED  IN  ONE  EYE.  5S 


In  comparing  the  estimation  found  in  this  way,  with  that  re- 
sulting from  actual  calculation,  we  will  find  a  certain  difference 
which  might  be  even  in  unfavorable  cases  as  much  as  1,  5  or  2.0, 
but  which  will  be  generally  much  less.  Such  a  difference  can  hard- 
ly be  avoided,  because  the  drawing  of  the  curves  and  the  mathe- 
matical calculation  can  not  be  exactly  in  congruity ;  but  as  in  the 
fourth  part  of  this  book  we  give  a  tabular  exposition  of  all  values 
gained  arithmetically,  we  are  always"  enabled  to  compare  these  with 
those  found  in  the  curves.  Exact  reading  of  the  curves  leads  to 
accuracy  of  the  result.  By  this  method,  the  handling  of  our  for- 
mula is  materially  simplified,  so  that  its  use  offers  no  difficulty 
whatever.  In  order  to  prove  this,  we  will  present  some  cases  to 
show  the  reader  its  convenience. 

§18.     Calculation  with  the  Formula. 
To  recapitulate  our  formula  : 


E  =  c  Vv  1/ M  j/'^ii:^  WVHi 

C  being  the  maximal  central  visual  acuity.  1^  P  the  visual  field,  and 


VM.  the  action  of  the  extrinsic  muscles  and  \  — — ^ —  V  P  1^  M 

is  the  ability  to  compete'.  The  latter  is  composed  (Chap.  VII., 
§  15)  of  the  arithmetical  proportion  of  the  central  visual  acuity  of 

both  ej'es  ^-^r — ^ ,  the  peripheric  vision  /Ip    and  the  muscular  ac- 

tion  Y^  >  with  the  provision  that  we  make  the  root  exponent  higher 
or  loAver,  as  the  case  may  be,  of  the  value  5,  7  or  10.  Let  us  now 
figure  some  examples  by  the  aid  of  this  formula : 

Example  I.  In  a  simple  case,  one  eye  having  suffered  a  trau- 
matic diminution  of  the  visual  acuity  which  has  a  value  of  V^  or 
0.5,  according  to  the  scientific  standard.  This  injured  person  fol- 
lows a  trade  which  has  higher  visual  demands,  for  instance,  is  a 
skilled  iron  worker.  In  such  a  case  the  maximum  C,  remains  un- 
changed, becanse  this  is  the  higher  visual  acuity  of  the  sound  eye 
which  remains  the  same.     C,  is  therefore  =  1,  V  P  the  visual  field, 

and  }f  M  the  muscular  action,  remain  unchanged.  These  three 
factors  represent  each  the  value  1.     In  this  case  the  unknown  quan- 

X 

tity  is  the  ability  to  compete,  1/  ^^   '  ^^  V^/ll 

C  -4-C 
'  ^    "   being  the   arithmetical    proportion   of   the   central    visual 

acuitv  of  both  eves       C,  the  uninjured  eye,  remains  =  1;C.,.  the  in- 


54  EXAMPLE^  VISION  IMPAIRED  IX  BOTH  EYES. 


jiired  eye,  should  be  reduced  according  to  our  supposition  to  0.5 
of  the  scientific  standard.  Looking  now  on  plate  I  on  the  absciss 
for  the  scientific  value  0.5  trace  this  line  upwards  until  we  meet 
the  economic  curve  (II),  and  from  the  point  where  the  line  cuts 
the  curve  we  go  to  the  left  and  find  there  on  the  ordinate  the 
economic  value  of  the  scientific  estimation  for  the  acuity  of  vision. 
As  the  plate  shows,  this  is  about  0.58.     By  inserting  this  value  in 

the  arithmetical  proportion  of  the  acuity  for  both  eyes,  into   '^    * 

we  hav?    - — ^^—  =  0.79.  This  we  insert  into  the  factor 

y^'"t^Yp"K¥  ;  ^'"^  t^^e^  ^^^'6    y  0.79  /  P  J^M      in  which  V  P 

4  X 

and  V  M  are  each  =  1;  the  whole  value  is  then  V  0.79  X  1  X  1. 
As  this  is  only  a  slight  injury  the  ability  to  compete  cannot  be 
impaired     very    much,    consequently  we  make    the  root   exponent 

10 

X  =  10.  This  value  V  0.79  x"!  ><  1  we  can  find  in  plate  V, 
curve  V.  We  look  simply  on  the  absciss  for  the  value  0.79,  trace 
the  line  from  there  upwards  until  we  meet  curve  V,  going  from 
there  to  the  left  we  find  on  the  ordinate  the  value  0.972.  If  we 
insert  this  value  into  the  formula  we  would  find  E  = 
1  X  1  X  1  X  0.972,  and  as  E,  in  our  formula,  has  always  been 
a  fraction  of  ],  it  must  be  multiplied  by  100  if  it  would  be  repre- 
sented as  a  percentage.  We  have  then  for  E==97.20.  If  we  compare 
this  value  97.20  with  the  example  I  (given  in  the  first  edition, 
Magnus,  p.  90),  which  was  97.69,  we  observe  that  the  difference 
between  the  two  values  is  very  small. 

Example  II.  As  a  second  case  we  will  take  impairment  of  the 
visual  acuit}'  in  both  eyes,  one  having  only  scientific  standard  of 
0.3,  the  other  of  0.4.  The  injured  person  may  have  a  vocation  de- 
manding higher  visual  powers.  How  would  we  here  figure  with 
our  formula  ? 


E  =  c  ...ax.v  p  /M  |/Cjf_a^— j.-^ 

The  factor  C  (maximum)  i.  e.,  the  highest  value  of  binocular 
visual  acuity  or  what  is  in  this  case  the  same  thing,  the  visual 
acuity  of  the  better  eye.  As  the  scientific  value  is  equal  to  0.4,  on 
plate  I  we  look  on  the  absciss  for  this  value,  go  to  the  curve  and 
find  that  it  is  professionally  equal  to  0.41.  The  professional  valu- 
ation of  the  different' values  for  the  visual  acuitv  mav  also  be  found 
on  Table  B,  p.  39.) 

The  factor  K  P  remains  unchanged  ==  1. 
The  factor  |/^M  remains  unchanged  =  1. 


REAL  SIMPLICITY  OF  THE  FORMULA.  55 


The  factor  )/^  "^^'x/PX/M  which  is  the  ability  to  compete 

C  I  C 

will  be  changed  only  in  the  part  — r— ^  because  the  field  of  vision 

and  the  ocular  muscles  are  not  impaired;  both  will, therefore,  be=l. 

C  +  C 
This  part      ^ — ^  would  resolve  itself  in  the  following  manner  as 

the  scientific  acuity  in  one  eye  has  diminished  to  0.4  and  in  the 

other  to  0.3,  as  we  find  out  by  the  curve,  the  scientific  standard 

C  4-  C- 
0.4  corresponds  with  0.41  and  0.3  with  0.25; — - — ^  is  therefore 

equal  to ^^^^^i^— =^=0.33.     The  entire  factor  of  the  ability 


TxKTl^ would  be,  if  we  enter  the  values  in 

X 

place  of  each  part:  K  0.33X1X1,  and  the  economic  equivalent  of 
this  value  we  can  find  directly  on  plate  V.  We  have  only  to  decide 
if  the  eyes  have  been  disfigured  from  leucomata  of  the  cornea  re- 
sulting from  the  injury  and  if  from  the  aesthetic  standpoint  the 
ability  to  compete  has  suffered.  If  this  be  the  case,  we  take  for 
the  root  exponent  5  and  look  on  plate  V  on  the  absciss  for  0.33; 
from  there  we  trace  upwards  till  we  meet  curve  III  and  read  to 
the  left  on  the  ordinate  the  economic  value  0.806.  The  ability  to 
compete  would,  therefore,  be  equal  to  0.806.  If  we  now  enter  all 
the  values  we  found  into  our  formula  we  transpose  it  as  follows : 


E=c„.ax.xi/p  xVm  X\^-^X\/  ?  XVM. 

E  =  0,41  X  1  X  1  X  0.806  =  0.33046  which  in  the  form 
of  a  percentage  equals  33.064  per  cent.  But,  if  we  should  take  in 
the  foregoing  example  a  slighter  impairment  of  the  ability  to  com- 
pete and  figure  it,  not  with  the  exponent  5  but  with  the  exponent 
10,  we  would  receive  the  result  E  =37.331  per  cent.  The  earning 
ability  in  this  case  would  be  4.285  per  cent  greater.  These  ex- 
amples should  be  sufficient  to  explain  our  methods. 

We  now  see  that  calculating  with  our  formula  is  really  simple. 
All  we  need  is  to  insert  the  values  of  the  individual  factors  into  the 
formula  as  we  find  them  on  the  plates.  When  this  simple  pro- 
cedure is  done,  the  formula  has  been  reduced  to  an  easy  multipli- 
cation example.  As  we  have  said  before,  by  reading  the  curves 
the  values  found  are  often  a  little  different  from  those  by  full  calcu- 
lation; but  as  this  difference  is  not  great  and  may  be  avoided  to  a 
great  extent  by  a  careful  reading,  this  fact  deserves  but  little  con- 


56  SIMPLICITY  OF  THE  FORMULA. 


sideration.  Besides  this,  the  values  found  by  reading  the  diagrams 
may  at  any  time  be  regulated  by  comparing  them  with  the  tabulated 
values  compiled  in  part  IV. 

We  believe  that  by  construction  of  the  curves,  the  calculation 
has  been  so  simplified  that  in  spite  of  the  seemingly  complicated 
composition  of  our  formula,  it  can  be  done  by  even  an  inexperienced 
mathematician.  Reservation  must  be  made  in  cases  where  the  in- 
jured person  had  possessed  before  the  time  of  the  accident  only  one 
eye  or  was  weak  sighted.  In  such  cases  special  modifications  of 
the  calculation  have  to  be  made  which  will  be  explained  in  the  fol- 
lowing chapters. 


PART  SECOND. 


Special  Consideration  of  Various  Ocular  Injuries 
and  Visual  Defects, 


58  INJURIES  OF  THE  VISUAL  FIELD. 


CHAPTER  IX. 


§19.     The  Relative  Importance  of  Disturbances  of  the  Visual  Field. 

In  estimating  defects  of  the  visual  field  we  should  remember 
that  two-thirds  of  the  binocular  field  belongs  to  and  is  controlled 
by  both  eyes  (yellow  area  of  Fig.l,  plate  IV.)  Under  certain  cir- 
cumstances these  disorders  have  only  monocular  effects.  For  in- 
stance, in  the  case  of  nasal  hemianopsia  (Schroeter  38,  p.  19  and 
our  Plate  IV,  Fig.  3.)  Such  limited  disorders  are  not  considered 
detrimental  to  the  earning  ability  because  the  field  of  vision  does 
not  suffer  restriction  of  its  normal  limits. 

An  experienced  calculator  may  easily  ascertain  the  arithmetical 
values  of  the  different  defects  of  the  visual  field,  but  for  complete- 
ness' sake  we  here  develop  these  values  for  a  series  of  disorders 
which  may  be  inserted  into  the  formula  for  the  earning  ability. 
The  following  explanations  are  considered  only  for  the  binocular 
field  of  vision : 

1.  Concentric  peripheric  contraction  of  slight  extent  with  nor- 
mal central  visual  acuity  not  extending  to  70°  (Chap.  7,  §  13)  is 
of  no  importance  in  this  relation  and  thus  may  be  omitted.  If  it 
exceeds  70°  but  does  not  go  beyond  60°,  the  field  of  vision  P  is  to 
be  inserted  as  two-thirds,  into  the  formula  for  the  earning  ability. 
The  earning  ability  is  then  80.012* ;  its  impairment  being  19.998. 

2.  Concentric  peripheric  contraction  of  a  greater  extent  with 
normal  central  visual  acuity  inaterially  exceeding  60°,  reaching  30° 
causes  two-thirds  loss  of  the  binocular  field,  the  remainder  of  which 
should  be  considered  as  one-third  in  the  formula  for  the  earning 
ability;  consequently  the  earning  ability  drops  to  54.65  (55  per 
cent.) ;  the  impairment  being  45.35  (45  per  cent.)  The  same  esti- 
mation is  given  for  any  limitations  between  30°  and  60°. 

3.  Concentric  peripheric  contraction  of  the  highest  degree  with 
remaining  normal  central  visual  acuity  always  means,  according  to 
our  supposition,  an  entire  inability  to  earn  (Ch.V,  §  11).  Schroeter 
(37,  p.  21)  takes  for  granted  that  in  such  cases  an  earning  ability 
of  25  per  cent,  may  still  exist  and  that  the  impairment  would  only 
be  75  per  cent.,  but  according  to  our  practical  experience,  we  can- 
not share  this  view  with  Schroeter.  A  man  who  has  only  central 
vision  left  is,  under  all  circumstances,  entirely  unable  to  work  and 
should  be  allowed  100  per  cent,  indemnity  for  the  loss  of  his  earning 
ability.     Practically  such  cases  are  -not  frequent,  at  least  not  as 


•For  simplicity's  sake  the  calculation  may  be  made  with  the  whole  numbers  80 percent. 
and  20  per  cent. 


COXTKACTIOX  AXD  HEMIANOPSIA.  59 

accidental  injuries.  The  double-sided  hemianopsias  which  are  like- 
wise very  infrequent  (Magnus  24)  and  of  which  there  has  only 
been  reported  one  traumatic  case  (Schmidt-Eimpler  35,  p.  181) 
are  considered  in  the  same  category. 

4.  Concentric  peripheric  contraction  of  the  field  of  vision  in 
one  eye  causes  diminishment  of  the  entire  field  of  one-sixth,  as  only 
the  exterior  portion  (the  red  or  blue  area  in  Fig.  2)  is  monocular. 
The  sound  eye  will  equalize  the  disorder  of  the  common  portion  of 
the  field  of  vision  caused  in  one-sided  concentric  contraction.  Even 
very  serious  concentric  contractions  limited  to  one  eye  will  impair 
the  total  value  of  the  field  of  vision  to  but  one-sixth;  the  earning 
ability  in  such  cases  is  90.45&  (90  per  cent.)  ;  the  imiDairment 
9.542  (10  per  cent.) 

5.  Homonymous  hemianopsia  dextra  vel  sinistra  causes  loss 
of  11/2  the  binocular  field  of  vision,  the  earning  ability  becom- 
ing, according  to  our  estimation,  68.302  (70  per  cent.)  ;  the  im- 
pairment 31.698  (30  per  cent.)  We  make  no  difference  between 
right  or  left-sided  hemianopsia,  but  for  the  purpose  of  indemnifica- 
tion give  them  the  same  value.  Schroeter  (37,  p.  17-18)  proposes 
to  allow  45  per  cent,  for  right-sided  hemianopsia  and  30  per  cent, 
for  left-sided,  because,  according  to  his  idea,  the  right  half  of  the 
field  of  vision  is  professionally  of  more  importance  than  the  left  one. 
While  it  must  be  admitted  that  the  loss  of  the  right  half  of  the  field 
of  vision  is  especially  embarrassing  in  the  beginning  for  certain 
occupations,  for  instance,  reading  and  writing,  and  is  more  in- 
convenient than  in  case  of  the  corresponding  loss  of  the  left  half, 
we  would  not  indemnify  hemianopsia  on  the  right  side  higher  than 
the  left,  for  it  is  always  a  question  whether  or  not  the  above  diffi- 
culties are  more  of  a  psychical  character  (Knies  16,  p.  28)  than 
due  to  the  actual  loss  of  vision ;  then  again  those  men  who  are  gen- 
erally exposed  to  accidental  injuries  do  but  little  reading  or  writing 
in  their  business;  and  then  the  person  ultimately  becomes  accus- 
tomed to  using  the  left  sides  of  the  visual  fields.  Besides  this 
there  are  many  occiipations  in  which  the  loss  of  the  left  field  would 
be  as  bad  as  that  of  the  right  and  for  left-handed  persons  the  loss 
of  the  left  side  would  certainly  be  inore  inconvenient  than  that  of 
the  right.  We,  therefore,  do  not  advise  a  higher  valuation  of  the 
right  field  of  vision. 

6.  In  the  case  of  vertical  homonymous  hemianopsia  the  loss 
is  equivalent  to  that  of  the  horizontal  forms:  Schroeter  (37,  p.  20) 
complicates  the  matter  again  in  that  he  makes  a  difference  in  the 
valuation  of  the  upper  and  the  loAver  half  of  the  field. 

7.  The  loss  of  both  the  temporal  halves  of  the  field  of  vision 
leaves  two-thirds  of  the  binocular  field,  but  this  is  not  any  more 
a  common  field :  the  left  half  belongs  to  the  right  eye  and  the  right 
half  to  the  left  (Plate  IV, Fig.  2)  :  but  this  condition  does  not  seem 
to  produce  special  disorders  in  actual  practice.  We  enter  the  value 
of  this  field  of  vision  as  two-thirds  P  in  the  formula  for  the  earn- 


60  he:miaxopsia  and  partial  defects. 


ing  ability  which  results  in  the  value  80.012  (80  per  cent.)  ;  and  for 
its  impairment  19.988  (20  per  cent.)  Schroeter  (37,  p.  19)  gives 
this  value  as  20  per  cent.,  making  our  figures  about  the  same. 

8.  By  the  absence  of  both  nasal  halves  the  common  field  suffers 
much  restriction,  as  there  are  no  more  peripheral  portions  common 
to  both  eyes.  The  two  temporal  halves  of  the  field  of  vision  left, 
touch  each  other  at  the  point  of  fixation  (Plate  IV,  Fig.  3),  the 
right  half  of  the  field  (blue  in  Fig.  3)  belongs  only  to  the  right  eye, 
the  left  half  (red  in  Fig.  3)  only  to  the  left.  Because  the  field  of 
vision  has  not  suffered  a  restriction  and  there  is  no  acuity  from  this 
condition,  the  earning  ability  is  not  curtailed. 

9.  Absence  of  the  nasal  half  of  the  field  of  vision  in  one  eye 
does  not  cause  diminution  of  the  entire  field  because  both  the  nasal 
halves  are  in  the  common  binocular  field  (yellow  area,  Plate  IV, 
Fig.  1.)  If  one  nasal  half  be  lost,  for  instance,  that  of  the  left 
eye,  it  only  causes  a  change  in  the  form  of  the  binocular  field.  The 
right  half  of  the  heretofore  common  field  would  now  be  monocular, 
belonging  only  to  the  right  eye;  the  left  half  of  the  entire  field 
would  have  the  peripheric  portion  belonging  to  the  left  and  a  cen- 
tral one  common  to  both  eyes  while  the  right  half  to  the  full  extent 
of  the  field  of  vision  belongs  only  to  the  right  eye  (Plate  IV.  Fig. 
4).  An  impairment  of  the  ability  to  earn  could  not  be  deduced 
from  this  condition  because  the  extent  of  the  total  field  of  vision 
has  not  suffered  restriction.  Cases  occurring  under  the  headings- 
of  8  and  9  could  be  used  to  prove  that  accidental  injuries  do  not 
always  cause  impairment  of  the  earning  ability  or  allow  of  claims 
for  indemnification.  This  is  noted  in  the  German  Accident  Insur- 
ance Law,  Chap.  I.,  §  3. 

10.  Loss  of  the  temporal  half  of  the  field  of  vision  of  one  eye 
from  the  point  of  fixation  to  the  outer  part,  for  instance,  of  the 
light  eye  (Plate  IV,  Fig.  5)  affects  only  the  range  of  the  total 
field  of  vision  supplied  by  the  right  eye  (blue  area.  Fig.  1)  Ac- 
cording to  our  classification,  the  binocular  or  total  field  would  be 
diminished  by  one-half  of  the  exterior  concentric  zone  (Fig.  1) 
which  would  he  one-sixth  of  the  total  field.  The  field  of  vision  left 
would  represent  five-sixths  of  the  original  amount,  but  the  right 
balf  of  the  common  field  would  now  be  only  a  monocular  one  be- 
longing only  to  the  left  eye ;  the  left  half  of  the  common  field  would 
be  unchanged,  the  field  would  then  take  the  form  of  Fig.  5,  Plate 
IV.  According  to  our  calculation  the  ability  to  earn  would  be 
90.458  (90  per  cent.)  ;  the  impairment  thereof  9.542  (10  per  cent.) 
Sehroeter's  estimation  (38,  p.  21)  for  the  latter  is  10.8. 

11.  Partial  defects  in  the  field  of  vision  in  only  one  eye  are 
very  seldom  injurious  to  the  working  ability,  if  they  affect  only  the 
common  range  of  the  total  field  (yellow  area,  Plate  IV,  Fig.  1), 
because  the  portion  lost  in  the  one  field  is  compensated  for  by  that 
of  the  other.  But,  if  the  particular  defect  reaches  into  the  mo- 
nocular part  of  the  total  field  (into  the  red  or  yellow  part  of  Fig  1), 


TABLE  OF  VISUAL  FIELD  DEFECTS. 


61 


a  diminution  and  -u-itli  it  a  disorder  of  the  field  of  vision  could  be 
shown.  In  such  cases  "vre  suggest  an  estimation  according  to  the 
quota  for  the  loss,  for  instance,  if  it  comprises  one-half  the  monocu- 
lar part  of  the  field,  the  earning  ability  would  then  be  90.458  (90 
per  cent.) ;  the  impairment  thereof  9.542  (10  per  cent.) 

12.  Partial  defects  of  the  binocular  field  should  be  valued  ac- 
cording to  their  extent.  The  physician  may  settle  how  much  is  left 
after  deducting  the  defect  from  the  binocular  field. 

13.  Total  loss  of  the  field  of  vision  of  one  eye  causes  diminish- 
ment  of  the  binocular  field  by  only  its  peripheric  part,  one-sixth 
(the  red  and  blue  parts,  Plate  IV,  Fig.  1.) 

We  condense  these  different  results  in  a  tabular  form : 

THE  EARNING  ABILITY  AND  THE  IMPAIRMENT  THEREOF  IN 

THE  DIFFERENT  DISORDERS  OF  THE  FIELD  OF  VISION 

WITH  REMAINING  NORMAL  CENTRAL 

VISUAL  ACUITY. 


VARIETY  OF  DEFECT. 


;  _  2  ^^.2 ;     Percentage. 


o  o  a «« 
•-  o 


"I  %  g-ojEarning  Impair- 
'h'3  S'®;  Ability,    meut. 


f  Partial  defects  in  the  field  of  one  eye ") 
I  Concentric  contraction  of  the  field  of  | 
1.  {      one  eye  )■ 

1  Absence  of  the  temporal  half  | 

1^  Absence  of  the  entire  field  of  one  eye  } 
{  Concentric  contraction  of  both  fields  ^ 


rt   I      reaching  to  60° 

'  1  Absence  of  the  temporal  half  of  both  \ 

I     fields  _  J 

o   I  Homonymous    hemianopsia    dextra  \ 

'  \  vel  sinistra  superior  vel  inferior  J 
.    (Serious     concentric     contraction    of 

■  \     both  fields  reaching  to  30° 

c  I  Total  concentric  contraction  of  both  ) 
(      fields  reaching  to  5°  j 

{  Absence  of  the  nasal  halves  of  both  \ 

g    I      fields  1^ 

■  I  Absence   of  the   nasal   half    of   one  ( 
L     field  j 


^      90,458     9,542 


% 

80,012 

19,988 

V2 

68,302 

31,698 

1/3 

54,650 

45,350 

\         ^ 

0,000 

100,0 

1 

100,00 

0,00 

The  foregoing  figures  are  made  for  both  higher  and  lower 
visual  demands  where  the  central  visual  acuity  remains  normal. 
In  cases  of  serious  injury  to  the  field  of  vision  where  the  ability  to 


62  COMPLICATED  riELD  DEFECTS. 


compete  suffers  it  is  necessary  to  figure  for  the  higher  demands 
where  the  oth  or  7th  roots  may  be  used.  This  is  done  in  table 
Ylla,  in  the  IVth  part  of  this  book. 

^20.     Disorders  of  the  Visual  Fields  Complicated  hy  Injury  to  the 
Central  Visual  Acuity  of  Different  Degrees  in  Either  Eye. 

As  in  practice  the  peripheric  "^dsion  as  well  as  the  central  acuity 
in  one  or  both  eyes  may  be  found  injured,  it  is  necessary  to  explain 
such  relations.  In  the  following  table  the  different  disorders  of  the 
field  of  vision  and  the  value  of  the  remainders  are  given  in  the  two 
left  columns,  while  in  the  right  column  we  find  figures  which  serve 
for  estimation  of  the  earning  ability,  in  all  cases  where  there  are 
disorders  of  the  field  of  vision  in  connection  Avith  damage  to  the 
central  acuity,  differing  in  either  eye.  We  first  settle  what  is  the 
arithmetical  value  of  the  remaining  field  of  vision,  for  instance,  it 
might  be  five-sixths ;  then  we  find  the  value  that  the  earning  ability 
would  have  if  the  otherwise  complicated  disorder  of  the  visual 
acuity  alone  existed.  We  then  read  from  tables  Y  or  VII  of  the 
fourth  part  without  an}'  trouble;  if,  for  instance,  one  eye  has  a 
Aisual  acuit}'  of  0.55  and  the  other  0.25,  according  to  table  V,  the 
earning  ability  would  be  61.078;  if  the  injured  person  follows  a  pro- 
fession demanding  high  vision.  Xow  we  multiply  this  value  G  1.078 
with  the  number  in  the  table  on  page  63  next  to  the  field  of 
vision;  as  in  our  example  the  arithmetical  value  of  the  field  of 
vision  Avould  be  five-sixths  we  would  then  have  to  multiply  61.078 
with  0.90-158;  this  would  give  us  an  earning  ability  of  55.250. 

Let  us  take  another  example;  in  concentric  contraction  of  the 
field  of  vision  reaching  to  30°  in  both  eyes  the  arithmetical  value 
of  the  remaining  field  would  be  one-third;  if  one  eye  has  central 
acuity  of  0.40,  the  other  of  0.20  and  the  demands  in  the  profession 
of  this  pai-ticular  individual  are  high,  both  the  central  acuities  of 
the  vision  would  have  an  earning  ability  of  36.273 ;  this  value  we 
would  multiply  with  the  number  we  find  in  the  table  next  to  the 
corresponding  value  of  the  field  of  vision,  i.  e.,  next  to  one-third 
— 0.5465,  from  wdiich  the  earning  ability  would  result  in  19.823 
and  its  impairment  80.177. 

If  one  eye  be  entirely  lost  while  the  other  suffers  impairment 
of  its  central  acuity,  the  numerals  given  in  the  table  on  page  63 
do  not  hold  good,  we  would  have  to  use  those  on  page  64;  the  calcu- 
lation is  the  same.  We  first  ascertain  (if  for  instance  one  eye  be 
totally  blind  and  the  other  has  only  a  visual  acuity  of  0.4  and  a 
field  of  vision  of  two-thirds,  provided  we  have  a  profession  with 
higher  visual  demands),  the  degree  that  the  earning  ability  would 
have  if  the  field  of  vision  would  not  have  taken  part  and  if  the 
acuity  of  vision  of  l>oth  eyes  had  suffered  to  the  above  extent,  which, 
according  to  table  V,  part  IV,  would  be  24.166;  this  value  we  mul- 
tiplv  with  0.57708  and  get  13.946  as  an  expression  for  the  degree 
of  the  earning  abilitv.  If  the  profession  demands  less  vision  we 
would  multiply  by  0.59238. 


TABLE  FOR  COMPLICATED  FIELD  DEFECTS. 


63 


AUXILIARY   DATA   FOR   THE  ESTIMATION  OF  THE  EARNING 

ABILITY    IN    DISORDERS  OF   THE  FIELD  OF  VISION 

WHERE  THE  CENTRAL  ACUITY  OF  BOTH 

EYES  IS  IMPAIRED  DIFFERENTLY. 


Variety  of  Defect. 


<D 

r3     O 

>2 

o 

o  <v 

o 

•-r!^ 

o  +=• 

Ul 

U   O 

> 

P=R 

1.. 


['Partial  defects  in  one  field. 

Concentric  contraction  (higher 
and  lower  degrees)  in  only 
one  field. 


4. 
5. 


y\  % 


Absence  of  the  temporal  half  | 
of  one  field.  j 

Small  concentric    contraction") 
ofboth  fields  to  60°.  | 

Absence  of  the  temporal  half  | 
ofboth  fields.  J 

Homonymous  hemianopsia 
dextra  vel  sinistra  superior 
vel  inferior. 

Great  concentric  limitation  of 
both  fields  reaching  to  30°. 

Total  concentric  limitation  of 
both  fields  reaching  to  5°. 


'A 


0.00 


Percentage. 


0.90458 


0.80012 


0.68302 


0.000 


f  Absence  of  the  nasal  halves  of  ^ 

I      both  fields.  | 

I  I 

I  Absence  of  the  nasal  half  of  \ 
y     one  field.  j 


Aa  these  disorders  of 
the  field  of  vision  do 
not  condition  an  im- 
I  pairmentof  theearning 
ability,  only  the  disor- 
der of  the  acuity  of 
vision  would  have  to 
be  indemnified. 


64  TABLE  FOR  LOSS  OF  ONE  EYE  AND  VISUAL  FIELD. 


AUXILIARY   DATA  FOR  THE  ESTIMATION  OF  THE  EARNING 

ABILITY  IN  LOSS  OF  ONE  EYE  COMPLICATED  WITH 

INJURY    TO    THE    VISUAL   ACUITY    AND 

VISUAL  FIELD  OF  THE  OTHER. 

These  four  numerals  are  given  by  the  following  operation;  whether 
the  peripheric  vision  P  is  limited  or  not,  we  always  have  for  the 
earning  ability : 


E 


=  c  VTili]/^^yThi==cyFhK^^^~^ 


==cvMy 


p     _|_  p        i  20 

^^^^  Vm  vt  V^ 


10 


The  quantity  C  V  M    [/  ^^-  Vll   ,  in  which  the 

muscular  action  M  has  to  be  regarded  as  abnormal,  for  a  case  in 
which  one  eye  is  lost,  is  taken  directly  from  table  V.  or  table  VI. ; 
to  find  E  it  must,  therefore,  be  multiplied  as  follows : 

20 

p  =  5^  multiplied  with  f^  V  %  =  0.90458. 

20 

p  =   2/3         -  "     YJ4  VVs  =  0.80012. 

20 

P=><         "  "     1^ 3^  V'l^  =  0.68302. 

P  =  >^         "  "     V34  v"r  =  0.54650. 

Where  we  have  to  figure  the  earning  ability  in  the  case  of  the 
loss  of  one  eye,  we  have  to  multiply  thus : 

For  Group  I.  I  For  Group  II. 

10 H 

P=3^withl/  3^  J^  3^  =0.73602    P=5^with|A3^  K  5^  =0.74685 

10  14 

P=8^5  "    /K5KM5=0.65580    P=X5  "    /Ms  1^5=0.69832 

10 14 

P=^    "    /%  V' ^  =0.57708    P=^    "    V"  2^  1^=0.59238 
Eegarding  these  fractions  see  Chap.  XI.,  §  23. 


PECULIAE  KELATION  OF  OCULAR  MUSCLES.  65 


CHAPTER  X. 


THE  IMPAIRMENT  OF  THE  EARNING  ABILITY  FROM  INJURIES 
TO  THE  EXTRA-OCULAR  MUSCLES. 


§21.     General  Bemarhs  Regarding  the  Importance  of  Injuries  to 
the  Extra-Ocular  Muscles. 

The  ocular  muscles  have  a  peculiar  position,  for  the  binocular 
act  can  only  exist  so  long  as  all  the  extrinsic  muscles  of  both  eyes 
are  functionally  undisturbed ;  as  soon  as  one  becomes  paralytic,  with 
the  beginning  of  diplopia,  monocular  vision  ends  and  for  profes- 
sional purposes  only  one  eye  is  at  the  patient's  disposal.  For  the 
person  with  two  normal  eyes,  a  paralysis  of  one  muscle  is  practi- 
cally identical,  for  professional  purposes,  to  the  loss  of  the  eye  and 
must  be  so  considered  in  determining  an  impairment  of  the  earn- 
ing ability.  If  the  injured  person  have  only  one  eye,  the  condi- 
tions are  quite  different ;  for  such  a  case  a  paralysis  of  one  external 
muscle  means  a  perceptible,  but  in  a  visual  sense,  a  relatively  insig- 
nificant impairment.  For  such  a  case  the  professional  act  of  vision 
is  not  annulled,  but  is  more  or  less  disturbed.  For  exhibiting  this 
peculiar  relation  of  the  ocular  muscles,  we  considered  in  the  for- 
mula for  the  professional  binocular  act  of  vision,  the  extrinsic  ocu- 
lar muscles  as  the  factors  of  a  product,  to  meet  this  demand ;  with 
the  paralysis  of  only  one  muscle  the  binocular  professional  act  en- 
tirely disappears  and  is  changed  into  the  monocular  form  because 
the  product  becomes  0  if  only  one  factor  becomes  0.  In  the  for- 
mula for  the  monocular  act  of  vision  we  express  the  arithmetical 
value  of  the  extrinsic  ocular  muscles  as  the  sum  of  6  numerals,  cor- 
responding with  the  number  of  the  ocular  muscles.  If  one  of  these 
be  lost,  the  sum  only  loses  this  numeral.  In  the  monocular  act 
of  vision,  as  well  as  in  the  binocular,  we  introduced  the  numerical 
expression  for  the  extrinsic  ocular  muscles  as  the  4th  root,  to  be 
able  to  give  expression  to  the  different  values  of  the  ocular  and 
muscular  functions  (Chap.  VI.,  §  11).  The  other  visual  functions 
have  a  different  value  than  the  muscular  movements,  which  may 
be  considered  only  auxiliary  functions  of  the  visual  act;  profes- 
sionally and  arithmetically  this  fact  cannot  be  neglected  and  so  the 
ocular  muscles  have  a  root  value  in  our  formula.  The  formula  for 
the  binocular  and  monocular  professional  acts  of  vision  have  been 
made  as  follows  (Chap.  VI.,  §  14)  : 


Binocular  Vision 


^^S2=C  f^  P  I'  (mim2m3m4m5m6)  (m/m2'm3''m/m5'm60 


Monocular  Vision 


=Si=Cy  ^  P    y  3^mi  +  mo  +  m3  +  mi  +  m5  +  m6 


66  UXCOMPLICATED  PARALYSIS  OF  OCULAR  MUSCLES. 


§22.     The  Estimation  in  Paralysis  of  Muscles  Uncomplicated  hy 
Other  Visual  Disorders. 

Ill  the  foregoing  paragraph  vre  again  developed  the  formiUas 
for  binociilar  and  monocular  vision.  We  will  now  try  to  figure 
the  extent  of  the  earning  ability  in  disorders  of  the  extrinsic  mus- 
cles of  originally  normal  eyes.  As  shown  already,  the  earning 
abilit}'  is  composed  of  the  two  factors  of  the  act  of  vision  and  the 
ability  to  compete;  the  formula  of  the  visual  act  is  shown  in  the 
foregoing.  In  order  to  figure  the  value  of  the  earning  ability  we 
will  now  have  to  state  the  formula  for  the  aljility  to  compete,  which 
is  the  xth  root  of  the  visual  act  (Chap.  IT.,  §  9;  Chap.  YIL, 
§  15) ;  in  every  ocular  injury  considered  aside  from  the  central 
acuity,  the  latter  has  the  greatest  influence  upon  the  visual  act 
and  is  placed  with  the  arithmetical  proportion  of  its  two  values  into 
the  formula  for  the  ability  to  compete.  If  the  injury  be  slight  we 
choose  the  root  exponent  10;  when  serious  the  exponent  5  or  7.  In 
the  case  of  the  loss  of  one  eye,  we  proposed  to  take  5  or  7  as  the 
root  exponent.  As  the  binocular  process  is  annulled  for  economic 
purposes,  the  individual  has  to  be  regarded  as  blind  in  one  eye; 
but  in  fact  there  is  really  a  difference  between  an  actual  one-eyed 
person  and  one  who  has  to  suddenly  rely  upon  the  monocular  act 
of  vision  on  account  of  paralysis  of  the  muscles,  because  there  is 
not  only  a  chance  of  having  the  paralysis  cured  but  later  there 
may  be  some  use  of  the  eye  which  has  been  excluded  from  the 
binocular  act  for  peripheral  vision,  as  soon  as  the  patient  has 
learned  to  suppress  double  images.  In  cases  of  paralysis  of  the  ex- 
trinsic ocular  muscles  we  would  insert  into  the  calculation  the 
ability  to  compete  with  the  root  exponent  of  10  which  we  have 
chosen  for  ocular  injuries  of  a  slight  or  moderate  degree.  The 
formula  for  the  ability  to  compete  in  the  monocular  act  woiild 
thus  be : 


y^'^'^i^j 


-A.  (mi  +  m-;  +  ms  +  m4  +  ms  +  me) 


and  the  formula  for   the  earning   ability  in  the   monocular   act 
would  be: 


Vj^pf 


E=lcr^Pr^im  +  m  +  ....) 


l/lC  +  0-,A V 


"Yz  (m:  +  mz  +  TCiz  +  mi  +  ms  +  me) 


After  having  developed  in  the  foregoing  formula  the  expression 
for  the  earning  ability  for  a  one-eyed  person,  we  may  figure  by 


PAIJALYSIS  OF  l^ECTUS  EXTERXUS.  67 


concrete  examples  the  impairment  of  the  earning  ability  in  case 
of  disorders  of  the  mnscles. 

Supposing  somebody  suffers  by  an  accident  a  paralysis  of  the 
rectus  externns  of  one  eye;  the  binocular  act  of  vision  would  be 
immediately  excluded,  because  if  the  individual  wishes  to  work 
at  all  he  must  cover  the  eye  and  therefore  exclude  it  from  the  act 
of  vision.  The  ability  to  earn  which  is  left  should  be  expressed 
by  the  above  formula  and  this  may  be  figured  by  using  the  curves 
in  plate  lY. ;  by  inserting  the  different  values  the  formula  would 
be  thus : 


E=l  X  0.913  X  0.904  X  fO.5  X  0.913  X  0.904=0.8254  X  J^O.4127 
=  0.8254X0.915  =  0.755241,  or  in  percentage  E  equals  75. 524, 
the  impairment  of  the  earning  ability  Avould  be  24.476  per  cent. 

Suppose  the  external  recti  become  paralyzed,  then  binocular 
vision  is  abolished  and  here  the  calculation  of  the  amount  of  dam- 
age to  the  working  vision  would  have  to  be  started  from  the  mo- 
nocular standard.  In  figuring  the  professional  loss  we  woiild  con- 
sider that  the  value  of  the  muscular  action  (as  stated  in  the  formula 
for  the  monocular  act  as  ^  mi  +  m2  +  m.j  +  m4+m.-,+mfi),  would  be 
diminished.  Because  the  muscular  action  of  the  one  eye  used  for 
seeing,  if  the  rectus  externus  be  impaired,  would  be  represented 
by  5  and  not  by  the  full  action  of  6 ;  it  would  therefore  be : 

ys    (mi  H-  m2  +  ms  +  mi  +  ms) 
or  more  simply,  two-thirds  of  five-sixths  M.     Entering  this  value 
into  the  formula  for  the  monocular  act  of  vision  it  would  be: 


IC 


r=^p7?^"j^Mf-i-^«y^"j/^ 


M. 


Transposing  this  by  the  assistance  of  the  curves  in  plate  T.,  the 
algebraic  formula  would  be  numerically  expressed  by  the  following: 

10 10 

E  =  1.093  X  0.863  V  0.5  X  0.913  X  0.863  =  0.78792  V  0.39396 
=  0.7879  X  0.911  =  0.717795  or  E  =  71.78  per  cent. 
If  in  a  case  having  the  same  acuity  of  vision  more  muscles bepara- 
lized  in  one  eye  than  in  the  other,  this  eye  should  be  regarded  as 
excluded  from  the  binocular  act  and  the  calculation  may  be  made 
with  the  better.  If  one  eye  have  a  lower  degree  of  vision,  both  hav- 
ing paralysis  of  the  exterior  muscles,  that  eye  which  has  the  better 
acuity  should  be  regarded  as  the  one  which  may  be  used  in  the  pro- 
fession, though  its  ocular  muscles  were  more  completely  damaged. 
In  the  following  table  the  earning  ability  and  impairment  thereof 
are  given  for  different  cases  of  paralysis,  it  l>eing  considered  therein 
that  the  eye  used  for  the  profession  has  a  working  acuity  of  at  least 
0.75  for  those  vocations  demanding  higher  vision  and  at  least  0.50 
for  those  with  lower  demands. 


68 


VALUATION  OF  OCULAR  MUSCLE  PARALYSIS. 


EARNING   ABILITY  AND  IMPAIRMENT  THEREOF  IN  UNCOM- 
PLICATED DISORDERS  OF  THE  EXTRINSIC 
OCULAR  MUSCLES. 


VARIETY  OF  DEFECT. 


t>  CO 

2^  « 


<  o 


.2^.2 
o  >,£ 


Xi 

03 

be 

a 
'3 

eg 


or:: 
*  i* 


1—0.75 

Paralysis  of  the  extrinsic  muscle  of  or 

only  one  eye,  1      1 — 0.50 

Paralysis  of  the  extrinsic  muscles  of  I 

both  eyes;    of  the  one  eye  used  1 — 0.75 

for  working  only  one  muscle  is  or 

paralyzed,  ^    1 — 0.50 

Paralysis  of  the  extrinsic  muscles  of  I 

both  eyes;    of  the  one  eye  used  '  1 — 0.75 

for  working  two  muscles  are  par-  or 

alyzed,  X    1—0.50 

Paralysis  of  the  extrinsic  muscles  of 
both  eyes;  of  the  one  eye  used 
for  working  three  muscles  are 
paralyzed, 


75.496 


1—0.75  I 

OR 

1—0.50    62.395 


Paralysis  of  the  extrinsic  muscles  | 
of  both  eyes;  of  the  one  eye  used 
for  working  four  muscles  are  par- 
alyzed, I  2^ 

Paralysis  of  the  extrinsic  muscles 
of  both  eyes;  of  the  one  eye  used 
for  working  five  muscles  are  par- 
alyzed, I  }4 


Paralysis  of  all  extrinsic  muscles  of 
the  eye  used  for  working,  i 


1—0.75 

OR 

1—0.50 


1—0.75 

OR 

1—0.50 
1-0.75 

OR 

1—0.50 


24.504 


71.805  '   28.195 


67.530     32.470 


37.605 


55.811  !  44.189 


46.125  I   53.875 


0.00    1100.00 


EPICKITIC  KEMAEKS.  69 


§23.     Epicritic  Remarhs  Concerning  the  Foregoing  Results. 

It  may  perhaps  at  first  sight  be  deemed  remarkable  that  we 
find  such  a  great  difference  between  the  earning  ability  in  the  case 
where  5  extrinsic  muscles  are  paralyzed  and  the  valuation  of  com- 
plete paralysis,  for  we  have  put  down  for  the  first  instance  an  im- 
pairment of  53.875  while  we  state  the  latter  as  100  per  cent.  The 
latter  figure  is  certainly  correct,  for  it  is  impossible  for  an  artisan, 
even  though  he  have  normal  acuity  of  vision,  who  suffers  paralysis 
of  all  the  extrinsic  muscles  which  move  the  eyeball  to  be  able  to 
earn.  The  consensus  of  authorities  gives  the  same  opinion  (Chap. 
VI.,  §  11).  In  specific  cases,  where  only  one  muscle  remains  func- 
tionable,  for  instance,  the  rectus  superior,  a  greater  impairment 
of  the  working  capacity  might  be  found,  for  this  muscle  has  but 
little  influence  upon  the  average  vocation.  If  the  rectus  intemus 
remains,  the  working  capacity  would  be  greater,  for  this  is  used 
much  more  often.  Therefore,  we  might  give  each  of  the  extrinsic 
muscles  a  different  valuation  (Chap.  YL,  §  13)  in  considering 
the  specific  demands  of  the  vocations  in  which  the  injured  person 
has  previously  labored,  or  we  may  get  around  this  point  by  giving 
a  higher  valuation  in  such  cases  to  the  ability  to  compete ;  thus 
figuring  not  with  the  10th  but  with  a  5th  or  6th  root  (table  Xllla, 
part  IV). 

By  such  a  method  we  are  enabled  to  simplify  our  mathematical 
calculations  in  specific  cases,  even  though  we  treat  all  the  ocular 
muscles  equally.  Thus  by  choosing  the  root  exponents  arbitrarily, 
the  physician  is  allowed  to  express  the  individuality  of  each 
case.  General  calculations  applicable  for  the  individual  values  of 
each  muscle  cannot  be  given  without  doing  violence  to  the  pecu- 
liarity of  the  particular  profession.  Thus  we  hold  it  for  the  best 
to  give  each  of  the  extrinsic  muscles  the  same  valuation,  that  is, 
one-sixth  of  the  total  value.  "We  regard  these  figures  as  generally 
applicable  as  the  lowest  standard  of  the  earning  ability  or  the  im- 
pairment thereof,  leaving  it  to  the  calculator  to  change  them  event- 
ually according  to  specific  demands  of  the  particular  case.  That 
paralysis  of  the  levator  palpebrae  superior  might  suspend  the  use 
of  the  affected  eye  is  self-evident  and  such  a  case  should  be  con- 
sidered professionally  as  one  of  monocular  vision. 


70  ACTION  IX  moxoculaeis:m. 


CHAPTER  XL 


§24.     What  Action  is  Necessary  if  the  Injured  Person  Has  Previ- 
ously Only  Had  the  Use  of  One  Eye  ? 

The  scientific  and  economic  conception  of  monocnlarism  is  not 
the  same.  "While,  from  a  scientific  standpoint,  a  person  is  to  be  re- 
garded as  one-eA'cd  whose  eyeball  has  been  removed  or  who  is  other- 
wise hopelessly  blind,  the  meaning  of  one-eyedness  (monocnlarism) 
developed  for  professional  life,  has  a  much  wider  range.  For  eco- 
nomic purposes  a  man  must  be  regarded  as  possessing  only  mo- 
nocular vision  who  has  but  the  one  useful  for  the  earning  of  his 
living,  if  the  other  has  insufficient  vision  for  this  purpose.  Tlie 
condition  of  the  poor  eye  and  the  degree  of  its  visual  acuity  is 
immaterial  in  this  consideration.  If  it  is  not  a  useful  eye,  that 
person  may  be  considered  to  have  but  monocular  vision  for  the 
purpose  of  earning  his  living,  for  he  could  not  follow  his  trade  if 
he  lost  the  more  normal  eye,  and  would  be  in  the  same  position  as  a 
man  who  had  originally  one  blind  eye  or  non^  at  all.  Although 
there  is  an  optical  and  scientific  difference,  the  economic  conse- 
quence would  be  the  same ;  both  would  be  unable  to  work,  although 
the  weak  and  professionally  insufficient  eye  in  the  one  case,  not 
being  entirely  blind,  is  of  inestimable  value  to  him ;  but  this  would 
have  nothing  to  do  in  judging  his  ability  to  earn ;  he  would  be  pro- 
fessionalh'  incompetent  if  the  uninjured  eye  is  unequal  to  the  de- 
mands of  the  trade.  Therefore,  for  our  purpose,  we  would  regard 
many  individuals  as  possessing  but  monocular  vision  who,  ac- 
cording to  the  scientific  standard,  can  see  more  or  less  with  both  eyes. 
Those  who  squint  and  suppress  the  image  of  one  eye,  those  who 
have  sufficient  refractive  error,  which  cannot  be  corrected  or  which 
lowers  the  acuity  of  vision  to  0.15  or  0.05  (according  to  the  visual 
recpiirements  of  the  trade),  those  who  have  congenital  monocular 
amblyopia,  etc.,  belong  to  this  class. 

In  the  case  of  an  individual  whose  previous  condition  would 
be  professionally  regarded  as  that  of  monocnlarism,  who  suffers 
an  injury  to  his  more  normal  eye,  how  would  we  estimate  the  earn- 
ing ability?  In  the  calculation  of  such  a  case  the  previous  con- 
dition has  to  be  considered  and  there  is  here  a  material  greater 
impairment  to  the  earning  power  than  in  the  case  of  a  person 
with  two  normal  eyes.  In  the  case  of  an  ocular  accident  hap- 
pening to  a  workman,  we  must  not  only  consider  his  own  peculiar 
ocular  conditions  but  the  side  of  the  insurance  company,  employer 
or  defendant  from  whom  he  may  be  seeking  indemnification  for  his 
injury,  so  that  we  must  be  sure  that  the  second  parties  are  not  bur- 
dened with  the  blame  for  an  impairment  which  the  laborer  had  be- 
fore the  accident.     "We  solve  this  difficult  problem  with  a  just  and 


ABILITY    TO    COMPETE   IX   MONOCULARISM.  71 


fair  consideration  of  tlie  claims  of  botli  parties,  when  we  start  with 
the  supposition  that  with  those  workmen  who  originally  possess 
only  the  working  use  of  one  eye,  the  condition  should  be  regarded 
as  normal,  and  therefore,  for  them  the  monocular  act  of  vision  is 
the  normal  one  and  equal  in  value  to  the  binocular  act  of  the  person 
with  two  normal  eyes.  Thus  out  of  fairness  to  the  employer  and 
the  Insurance  Company  and  the  workman  himself,  we  would  not 
arithmeticall}'  consider  the  scientific  standard  of  binocular  vision 
in  the  case  of  a  workman  who  has  entered  into  his  employment 
with  only  one  working  eye  and  who  has  suffered  an  injury  to  it. 
We  calculate  his  claims  in  the  same  manner  in  which  we  figure 
the  ability  to  compete  (Chap.  IV.,  §  9;  Chap.  VII.,  §  15),  wliich 
is  equal  to  the  visual  act  and  acuities  of  vision  of  both  eyes  in  an 
arithmetical  proportion  thus: 


y 


^'  +  ^'  VTVm. 


2 

As  in  estimating  the  ability  to  compete  of  a  person  possessing 
monocular  vision  who  has  suffered  injury  to  it  through  an  accident, 
we  put  the  visual  acuity  of  one  eye  with  its 'full  va'lue  C  under  the 

V  ;  thus  the  formula  for  the  ability  to  compete  of  the  one-eyed 
person  would  be : 


r 


t'  •'  P  VK 


This  formula  leads  to  the  same  results  as  that  which  we  get  for 
injuries  to  the  visual  acuity  in  binocular  vision ;  as  by  this  method, 
a  man  who  has  originally  one  eye  would  be  impaired  through  an 
accident  to  his  working  eye  to  the  same  extent  that  occurs  in  a 
binocular  case.  When  an  employer  hires  an  individual  who  is 
originally  in  possession  of  but  one  eye  or  who  has  practically  only 
monocular  vision,  he  does  this  under  the  supposition  that  this  de- 
fect does  not  hinder  him  in  his  Avork  and  regards  this  condition 
as  the  normal  for  this  particular  individual.  If  this  be  the  case, 
the  ability  to  compete  of  such  a  man  may  be  deemed  normal  and 
in  estimating  his  earning  ability  we  would  take  his  ability  to  com- 
pete as  the  10th  root  of  the  normal  binocular  vision  of  the  man 
Avith  two  eyes.  But  regarding  the  chances  of  obtaining  work  we 
Avould  repeat  that  there  is  a  difference  even  in  cases  of  monocular 
vision;  for  instance,  if  a  person  has  in  one  eye  an  irregular  astig- 
matism which  diminishes  the  acuity  below  the  working  standard 
so  that  he  cannot  use  this  eye  in  a  profession  with  higher  ocular 
demands,  for  economic  purposes  he  would  professionally  be  deemed 
one-ej^ed,  but  he  would  be  able  to  find  work  much  easier  than 
another  laborer  who  has  a  bad-looking  blind  eye,  for  instance  cor- 
neal staphyloma,  through  blenorrhoea,  etc.  Therefore,  we  would 
make  an  aritbmotieal  difference  between  such  cases,  takins:  as  the 


72  EXAMPLE  OF  INJURY  IN  MONOCULARISM, 


exponent  of  the  root  for  the  ability  to  compete  the  number  10, 
where  there  is  a  good-looking  eye  and  one  not  entirely  blind ;  but  in 
the  case  of  a  person  with  a  bad-looking  blind  eye,  for  the  higher 
ocular  demands,  we  would  take  the  exponent  5,  and  for  lower  ones 
7 ;  which  are  the  same  values  that  we  took  in  the  case  of  a  workman 
who  had  originally  two  normal  eyes.  We  give  the  following  ex- 
ample :  Supposing  the  vision  of  the  sound  eye  in  the  case  of  a  one- 
eyed  workman  be  reduced  to  0.65  (scientific  standard)  our  for- 
mula would  be  the  following : 

i      

E  =  C  /  P  K^nii  +  m2  +  m3  +  mi  +  ms  +  me) 


^  GVvr 


(m,  +  mo  +  ms  +  mi  +  m.^  +  m,-,) 


As  in  this  ease  the  visual  field  and  the  ocular  muscles  are  not 
impaired,  and  therefore  1,  the  reduced  formula  would  be : 


E 


=  G]riv  iM  G\'  1}/ 1 


Substituting  the  professional  valuation  of  the  scientific  standard 
for  0.65  from  our  curves  on  plate  I  equals  0.833,  and  entering  it 
now  into  the  formula  which  would  be: 


E  =  0.833  X  1  X  1  K  0.833  X  1  X  1 


the  value  ]/  0.833  will  be  found  in  the  curves  of  plate  Y. ;  if  for 


instance,  we  take  the  root  exponent  x:=10,  then  y  0.833  =0.982, 
which  leaves  the  formula  thus :  E  =  0.833  X  0.982  =  0.818006 
or  E=81.801  per  cent. 

In  the  case  of  injury  to  the  visual  field  in  an  originally  one- 
eyed  person  we  would  figure  according  to  the  following:  the  field 
of  vision  of  a  one-eyed  person,  as  we  have  seen  in  Chap.  VI.,  plate 
IV.,  Fig.  1,  is  narrower  by  one-sixth  than  the  field  of  vision 
of  a  normal  person.  If  the  right  or  left  eye  is  gone,  either  the 
right  or  the  left  temporal  segment  of  the  common  field  of  vision 
blue  or  red  in  Fig.  1,  plate  IV.)  would  be  missing.  Thus  accord- 
ing to  our  arrangement,  the  monocular  field  contains  5  parts  of  the 
binocular  one,  which  are  3^  of  zone  I,  3^  of  zone  II  and  ~A  of 
zone  III.  Thus  if  we  desire  to  make  an  arithmetical  calculation  of 
the  limitation  to  the  monocular  field  of  vision,  we  should  start  with 
this  five-part  arrangement  and  express  the  impairments  by  fifths. 
The  different  estimates  of  damage  to  visual  field  would  thus  have 
the  following  values : 


VISUAL  FIELD  IN  MONOCULAKISM.  73 


Loss  of  the  temporal  half  there  is  retained 3^ 

Loss  of  the  nasal  half  there  is  retained j/s 

If  the  concentric  contraction  reaches   30°    the  value 
remaining  is 3^ 

If  the  limitation  on  the  nasal  side  is  more  than  45°,  on  the 
temporal  side  70°,  below  65°,  above  40°,  the  value  of  the  remaining 
field  of  vision  is  ^5.* 

In  calculating  the  amount  of  damage  to'  economic  vision  from 
injuries  to  the  monocular  field,  we  insert  in  our  formula  for  the 
earning  ability  of  the  monocular  act  of  vision  for  the  value  P  the 
valuation  of  the  remaining  field  of  visison.     Our  formula  being : 

4 

E  =  C  ]/YV  (mi  +  m7+  ms^  m7  +  ms  +  me) 

]  C  VYV  (mi  +  mo  +  m3  +  m,  +  mr,  +  m,) 

Supposing  the  remaining  portion  of  the  field  of  vision  equals  two- 
fifths,  the  central  visual  acuity  C  and  the  valuation  of  the  ocular 

4 

muscles  V  (nn  +  ms  +  ms  +  m*  +  ms  +  ms)  remain  unimpaired, 
being  equal  to  1,  the  reduced  formula  would  be : 

X 

E  =  1  lA  2^  ]/  rf  1  vi^ /T 

and  as  each  1^1,  the  resultant  formula  would  be : 

X 

^  =  iv  yk  1  y  1  r'H  1 

and  which  can  be  readily  figured,  or,  if  preferable,  the  valuation 
can  be  easily  found  with  the  assistance  of  the  curves  in  plate  Y. 


•The  value  ^is  above  figured  is  thus  explained :  The  limitation  reaching  temporally 
to  60°  from  the  fixation  point  leaves  -45  of  the  field  of  vision,  of  which  a  part  is  lost  when 
the  limitation  above  is  over  40°,  below  over  65°  and  on  the  nasal  side  over  45°,  which 
we  estimate  as  a  %  loss  of  the  remaining  %  of  the  field;  therefore,  there  remains  % 
ofy5  =  %5- 


74  MEANING  OF  ECONOMIC  WEAK  VISION. 


CHAPTER  Xn. 


ESTIMATION  OF  ACCIDENTAL   INJURIES  IN   THOSE  CASES  IN 

WHICH  ONE  OR  BOTH  EYES  DID  NOT  POSSESS,  BEFORE 

THE    ACCIDENT,   SUFFICIENT    NORMAL 

CENTRAL  VISUAL  ACUITY. 


§25.     The  Cleaning  of  Weah  Vision  from  an  Economic  Standpoint. 

There  are  many  cases  to  which  trauma  occurs  in  which  the 
eyes  had  some  previous  disorder  or  disease  affecting  the  visual 
acuity,  field  of  vision  or  the  ocular  muscles.  It  is  more  especially 
defective  visual  acuity  that  is  here  considered.  A  recent  article  by 
Walther  (47)  who  reported  upon  the  examination  of  the  eyes  of 
2,672  active  workmen  (printers,  metal  workers,  wood  workers,  glass 
and  porcelain  workers,  woolen  workers,  electrical  and  gas  workers) 
fouiul  that  exclusive  of  refraction  defects  that  could  be  corrected 
by  lenses,  611  were  more  or  less  amblyopic.  Of  these  347  (63  per 
cent.)  had  congenital  defects;  224  (36  per  cent.)  acquired  defects: 
95  being  of  doubtful  origin.  In  15  per  cent,  the  poor  sight  had 
been  caused  by  the  work.  Every  practitioner  knows  how  common 
are  opacities  of  the  cornea  and  other  disorders  of  the  ocular  media 
whicli  affect  the  visual  acuity  in  those  classes  of  people  that  fur- 
nish laborers  and  artisans.  Considering  further  how  many  cases 
of  strabismus,  anisometropia,  high  grades  of  astigmatism  and  re- 
fractional anomalies  which  are  accompanied  by  weakness  of  vision 
of  one  or  both  eyes,  we  will  have  to  admit  that  many  cases  of  ocular 
accidents  have  previously  had  weak  sight  and  whose  acuity  of  vision 
did  not  reach  the  economic  limit,  i.  e.,  0.75  or  0.50.  If  the  physi- 
cian, who  is  called  to  estimate  the  amount  of  visual  damage,  finds 
inflis]-)utable  proof  that  there  was  weakness  of  vision  before  tbe 
aeeifleut,  what  should  be  his  action  in  fixing  the  ability  to  earn? 
If  after  an  accident  to  both  eyes,  he  finds  only  a  visual  acuity  of 
0.40,  he  must  decide  regarding  the  previous  condition  of  the  eyes, 
for  the  weakness  of  vision  after  the  accident  may  not  be  solely 
the  result  of  the  trauma,  but  due  in  part  or  whole  to  causes  not 
connected  with  it.  In  such  cases  particular  care  must  be  observed 
in  the  arithmetical  estimation  of  the  resultant  damage  to  vision  ;  we 
are  certainly  not  justified  in  drawing  conclusions  from  uncertain 
suppositions  about  the  earning  ability  before  the  accident.  If  we 
cannot  get  reliable  information  concerning  the  injured  person  of 
the  results  of  previous  examinations,  our  estimation  would  depend 
entirely  upon  the  impression  gained  by  the  present  condition  of  the 
eve.     There  are   many  individuals   who   combine   an  astonishing 


IMPRACTICABILITY  OF  GENERAL  VISUAL  EXAMINATIONS.  75 


amount  of  working  and  earning  ability  with  exceptionally  low  visual 
acuit}',  as  has  been  shown  by  Groenouw's  examples.  Therefore,  we 
cannot  give  each  individual,  whom  we  suppose  had  a  weakness  of 
vision  before  the  accident,  an  earning  ability  in  proportion  to 
the  hypothetic  degree  of  this  weakness.  The  possibility  or 
even  probability  is,  that  this  weak  sighted  individual  pos- 
sessed a  greater  ability  to  earn  than  might  be  supposed  accord- 
ing to  objective  results.  Therefore,  the  physician  should  only  con- 
sider reliable  communications,  such  as  an  exact  functional  examina- 
tion of  the  eyes,  regarding  the  previous  extent  of  the  weakness  of 
vision  in  the  particular  case.  If  he  has  no  such  data,  each  person 
suffering  from  an  ocular  accident  should  be  regarded  as  formerly 
normal;  for  even  if  there  is  a  conviction  that  there  was  formerly 
a  weakness  of  vision,  justice  demands  that  an  arithmetical  valu- 
ation of  the  former  condition  could  be  secured  only  by  a  previous 
functional  examination.  But  this  general  rule,  of  course,  may  be 
laid  aside  in  those  cases  in  which  there  are  decided  opacities  of  the 
ocular  media,  congenital  defects,  which,  through  their  appearance, 
have  evidently  existed  for  a  long  time  previous  to  the  accident,  etc. ; 
the  physician  may  positively  know  that  such  have  precluded  the 
possibility  of  previously  existing  good  working  conditions.  As  this 
German  Accident  Insurance  law  was  passed  with  benevolent  inten- 
tions of  protecting  the  workingman,  we  divine  that  his  interest 
should  be  placed  foremost.  If  we  do  this,  we  should  stick  to  the 
principle  that  a  former  weakness  of  vision  should  diminish  the 
claims  for  indemnification  of  injured  workingmen  only  in  such 
cases  where  the  extent  of  the  weakness  of  vision  before  the  accident 
has  been  fixed  by  a  reliable  functional  examination.  Certainly 
the  Utopian  idea  of  examination  of  the  eyes  and  other  organs  of  all 
workingmen  before  taking  employment  and  at  stated  intervals 
thereafter,  according  to  Zehender  and  others  of  our  colleagues, 
would  fix  this  matter,  but  such  is  impractical  except  for  the  rail- 
road, army  and  other  kindred  services.  A  systematic  examination 
could  only  be  made  by  a  qualified  oculist,  and  it  would  be  impos- 
sible, as  many  factories  are  in  small  towns  that  cannot  support  an 
oculist.  Likewise  the  financial  question  renders  it  impractical,  for 
neither  the  workingman  nor  the  employer  is  at  present  willing  to 
stand  the  expense,  and  surely  the  physician  should  not  be  jequired 
to  give  his  time  for  nothing,  especially  considering  that  he  would 
have  to  write  a  certificate  and  accept  responsibility  in  every  single 
case.  Then  again,  one  examination  is  not  sufficient :  each  one 
should  be  re-examined  from  time  to  time,  as  has  been  done  in  the 
railroads.  For  the  latter  service,  re-examinations  are  conducted 
every  few  years  or  upon  applications  for  promotion.  Such  examina- 
tions are  certainly  demanded  for  this  class  of  workmen,  for  upon 
their  eye-sight  and  physical  condition  depends  the  lives  of  many 
others. 


76  WEAK  VISION"  EXISTING  BEFORE  THE  ACCIDENT, 


§26.  E.-itiinaiion  of  Hte  EaruiiKj  Abililij  in  Case  Weakness  of 
Vision  Existed  Before  the  Accident,  Which  Can  Be  Nu- 
merically Fixed  Through  a  Former  Functional  Exami- 
nation.\ 

If  a  workman  suffers  impairment  of  his  visual  acuity  by  an  ac- 
cident and  data  exists  of  his  former  condition,  this  weakness  should 
be  taken  into  account  in  estimating  the  damages  caused  by  the  acci- 
dent. If  in  such  a  case  we  had  based  our  estimation  upon  the 
ocular  conditions  of  the  formerly  normal-sighted  person,  the  injury 
would  then  receive  an  indemnification  which  is  too  high;  beiug 
recompensed  for  the  loss  of  a  something  which  he  never  possessed. 
To  prove  the  correctness  of  this  assertion,  let  us  look  at  the  follow- 
ing case : 

A  w^orkingman  coming  under  Group  I  who  had  in  one  eye  for- 
merly only  0.60  visual  acuity,  suffers  an  injury  which  diminishes 
this  to  0.40,should  he  be  indemnified  the  same  as  if  he  had  formerly 

normal  visual  acuitv?     This  num  has  still  -*^^>^  of  his  former 

0,60 

vision,  but   if  his  former  weakness  would   not   l)o  considered,  he 

would  be  indemnified  as  if  his  resultant  vision  was  only  ^^-^^^ 

Thus  allowances  for  the  former  visual  acuity  in  cases  will  have  to 
be  made  where  it  is  known.  Thus,  in  the  estimation  of  such  a  case, 
we  W'Ould  not  enter  the  quantity  0.40  into  the  formula,  for  this 
would  result  in  too  great  indemnification,  but  another  X,  which 
bears  the  same  ratio  to  the  unity  of  the  particular  group  (here 
higher  visual  demands,  0.75)  as  the  remaining  acuity  of  vision 
after  the  accident  (0.40)  to  the  former  (0.60)  as  in  the  follow- 
ing proportion : 

X  :  0,75  =  0.40    :  0,60 

X  =  0.75  X^40  =  0,50 
0,60 
As  in  those  cases  the  use  of  such  an  auxiliary  C[uantity  is  neces- 
sary, we  wall  introduce  for  it  a  special  expression : 

Definition:  If  n  is  the  normal  acuity  of  vision  (for  working- 
xnen  with  higher  visual  demands  n  =  0,75  ;  for  workingmen  with 
lower  demands  n  =  0,50);  ni  the  original  acuity  of  vision  of  the 
weak-sighted  and  Ci  the  acuity  of  vision  after  the  accident.* 

We  would  understand  under  "modified  visual  acuity,"  an  acuity 
Ci' which  suffices  for  the  proportion  Ci':n  =Ci:ni  from  which  we  get 

the  equation :     Ci'  =  n  - . 

^ ni 

tin  forensic  praetice  the  following  examples  will  be  seldom  found.  Considerable  space 
is  siven  for  such  eases  here  to  show  that  our  rules  are  universal  and  adapted  to  the  most 
tomplicated  as  well  as  the  simpler  cases. 

*In  naine  the  readinp;  tables,  the  reranininp:  visual  acuity  after  an  injury  would  be  the 
scientific  standard  and  would  have  to  be  changed  into  the  professional  one. 


CALCULATION  OF  CASES  OF  PREVIOUS  WEAK  VISIOX.  77 

This  expression  would  be  used  for  the  original  visual  value  un- 
der the  following  circumstances :  if  a  person  begins  a  trade  or 
vocation  with  a  weaker  normal  visual  acuity  than  n  which  we 
would  denominate  ni,  and  then  has  this  eye  injured  so  that  ulti- 
mately there  is  a  visual  acuity  of  Ci,  the  estimation  of  his  indemni- 
fication should  be  based  upon  the  modified  visual  acuity  c/  and 
not  the  original  acuity  Ci-  Tf  the  person  be  weak-sighted  in  both 
eyes,  n2  and  C2  mark  the  values  for  the  second  eye,  corresponding 
to  the  quantities  iii  and  Ci  ;  thus  the  modified  visual  acuity  c/  must 
be  introduced,  as  the  act  of  vision  is,  in  this  case,  dependent  upon 
two  modified  acuities  c/  and  c^  .  One  of  these  quantities  would 
generally  be  greater,  if  both  be  equal,  it  is  immaterial  which  we 
choose;  one  should  be  marked  Ijy  c'max.  The  formula  for  the  visual 
act  would  thus  be : 

4 
S2   =  C',„ax.   VTVlL 

As  at  present  we  only  deal  with  the  factor  of  visual  acuity,  consid- 
ering in  our  examples  that  the  peripheric  vision  and  muscular 
action  are  normal,  thus  estimating  their  value  as  1  in  the  equation : 

S2  =  C'„,ax.  X  1  X  1. 

We  have  now  found  a  value  for  the  visual  act  S  and  will  have 
to  consider  the  second  factor,  the  ability  to  compete  K,  for  the  esti- 
mation of  the  ocular  earning  ability  E.  This  quantity  K  we  have 
identified  for  our  purposes  with  the  act  of  vision  itself  but  with  a 
difference,  whereas  we  made  this  factor  dependent  only  upon  the 
miximum  of  the  central  acuities  of  both  eyes,  we  introduced  into 
the  other  in  its  stead  the  arithmetical  proportion  of  the  central 
visual  acuities.  And  as  in  our  case  we  must  regard  the  modified 
acuities  c/  and  c/  as  ideally  existing,  it  would  seem  at  first  glance 

as  if  we  had  to  figure  with  these  and  to  insert  for  K  the  value 

gj'  _j_  g^'         "  _         * 

K  = g ,  where  we  again  disregard  the  (juantities  |/  p  and  ]/  M. 

Such  a  supposition  would  be  in  opposition  to  statements  previously 
made.  Indeed,  the  ability  to  compete  is  a  quantity  which  depends 
more  upon  others  than  upon  the  individual  himself,  and  while  w^e 
had  to  say  in  figuring  the  visual  act :  The  visual  acuities  Ci  and  C2 
have  for  the  individual  the  valu'^  c,'  and  C2'  ;  we  cannot  definitely 
assert  a  value  for  this  quantity  as  it  is  dependent,  to  a  small  degree, 
upon  the  individual  himself.  If  in  the  estimation  of  K  we  would 
take  as  auxiliaries,  the  modified  visual  acuities  c/  and  d'  we  would 
express  therewith  the  idea  that  the  acuities  of  vision  Ci  and  C2  have 
in  other  cases  these  modified  values  and  this  supposition  is  not  sup- 
ported by  facts.     This  simple  reflection  forces  us  to  accept  K  in  the 


78  CALCTLATIOX  OF  CASLS  OF  PREVIOUS  AVEAK  VISIOX. 


form  K  =  -^-  — ^  and  inserting  this  and  the  value  of  the  f(jrmer 

^  X 

vision  into  the  general  formula  for  the  earning  ability   E  =  S  ^  K 
the  result  would  be : 


p   _    ..               1/    Cl    +    C2 
tj  C    ,„ax.    V 


It  would  seem  almost  as  if  a  great  many  tables  were  desirable  for 
figuring  the  above  formula,  because  c'max.  and  -~^ — ^  may  have  many 

different  values  and  allow  of  numerous  combinations,  but  it  is 
possible  to  make  use  of  the  above  expression  for  E  without  going 
into  such  detail.  "We  will  use  the  former  expressions  and  mark 
for  c  max.  the  greater  of  the  two  visual  acuities  Ci  and  C2 ;  then  if, 
for  instance,  n  =  0.75  or  0.50,  we  estimate  from  our  two  main 
tables  Y.  or  VI.,  part  IV.,  as  an  auxiliary  quantity  an  earning 
ability  E  which  is  given  in  the  proportion : 


E   =   C,„ax.f^+"* 


2 

out  of  this  we  get  the  value  of  the  10th  root 


} 


Cl  +  C2  E' 


■<  C     max. 

and  bv  insertino;  this  value  into  the  above  formula  for  E  we  get 


E  —  c'         l/ci  +  C2 

•L'  <-      max.    W   ~ 

which  reduced  to  the  extremely  simple  equation, 

Ti   C'  max.  ^  E^ 

C  max. 

whose  figuring  is  possible  without  any  difficulty.  As  we  have 
already  shown  the  quantities  c  max.  and  c'  max.  must  be  replaced  by 
their  professional  values.  How  these  can  be  readily  estimated  in 
eases  where  table  II.  is  not  available  will  be  shown  by  examples. 

Of  course,  the  above  formula  for  E  has  been  deduced  under 
the  supposition  that  the  visual  field  and  muscular  action  remains 
normal.  The  same  method  may  be  readily  used  for  finding  the 
reduced  visual  field  or  reduced  value  of  the  ocular  muscles.  In- 
deed, the  reduced  quantities  P  and  M, which  were  omitted  in  our  last 
formula  for  the  earning  ability  E,  will  form  with  the  same  amount 
part  of  the  auxiliary  quantity  E'  and  are  taken  as  such  in  our 


EXAMPLES.  79 


table,  which  furnishes  the  visual  aciiitics  of  ci  and  Cg  with  re- 
mainders of  P  and  M,  the  vakie  E'.  Therefore,  we  do  not  need  to 
estimate  the  impairments  of  P  and  M  separately. 

In  order  to  quickly  ascertain  in  all  cases  of  weakness  of  vision, 
the  corresponding  ability  of  earning,  the  following  has  to  be  done : 

We  take  the  earning  ability  E'  belonging  to  the  really  existing 
visual  acuities  ci  and  Ca  from  one  of  the  corresponding  tables, 
figure  the  modified  acuities  of  vision  c  max.  and  c'  max.,  multiply  E' 
with  the  greater  figure  c'  max.  and  divide  the  product,  by  the  greater 
of  the  two  values  ci  and  Cg  (c  max.),  but  the  two  quantities  c  max  and 
c'max.  have  to  be  inserted  in  their  professional  values;  the  resulting 
quotient  is  the  desired  earning  ability.  To  show  how  simple  the 
calculation  really  is  we  will  exhibit  one  example  each  of  the  differ- 
ent possibilities  which  we  divide  into  the  following  four  groups : 

Group  I — One  eye  is  normal,  the  other  originally  weak-sighted. 

Group  II.  Both  eyes  are  originally  weak-sighted  to  equal 
degrees. 

Group  III.  Both  eyes  are  originally  weak-sighted  to  different 
degrees. 

Group  lY.  One  eye  is  blind  and  the  other  originally  weak- 
sighted. 

To  each  of  these  four  groups  may  be  added  the  accidental  in- 
juries in  their  different  forms.  In  the  following  we  will  explain 
the  single  groups  with  the  different  accidental  possibilities. 

§27.  Group  I.  One  Eye  is  Normal,  the  Other  OriginaUij  Weak- 
Sigh  ted. 

In  all  the  example?  of  thi;^  group  we  deal  with  an  individual 
Avhose  work  requires  higher  ocular  demands  (thus  n^O.75)  and 
whose  eye  1  has  at  least  a  visual  acuity  of  ni  =  0.75  and  whose  other 
has  perhaps  only  ni;=0.60. 

Example  1.  *The  normal  eye  remains  sound  (ci=0.75).  the 
acuity  of  vision  of  the  other  eye  2  is  diminished  through  an  in- 
jurv'  to  C2=  0.30  the  modified  visiial  acuities  are: 

c/=n  ''-=0.75^.11=0.75, 
ni  0.75 

c/=n  ''^=0.75  ^•|^=  0.375. 
n2  0.60 

Table  Y.  of  the  fourth  part  gives  the  earning  ability  E  belonging  to 
c,  =  0.75  and  c?  =  0.30  as  E'  =95.41. 

The  maximum  of  the  real  acuities  of  vision  is  Ct  =  0.75,  of  the 
modified  acuities  of  vision  alsoc/=  0.75,  and  as  both  values  cor- 
respond according  to  the  table  on  p.  42  with  1,  the  desired  earning 

ability  E  will  be :     E  =  ""'  '"""  ^'  -  L>< ^M^  =95.41. 


*In  these  example.'*  figures  taken  from  tables  in  Part  IV  refer  to  theTIGermaneditionof 
Maprniis'book  in  which  the  perpentaces  are  worked  over  to  the  thousandths.  For  practical 
UKe  the  American  Author  only  accepts  them  to  tenths  and  has  thns  published  the  tables. 


80  EXAMPLES. 

Example  "2.  If  the  eye  1  is  sound  (ci  =  0.75)  while  the  acuity 
of  vision  of  the  other  eye  2,  is  reduced  to  C2=0,  the  modified  acui- 
ties are : 

c,        „^_0.75      „^_ 
Ci=n      =  0. <o  „  „^  ^0.  it>, 
ni  0.  r5 

c,,  =  n        =  0.  /  o  .^  „  „  =  0. 
n-i  0.60 

to  Ci=:0.T5  and  Ci'=U  belongs  according  to  table  Y.,  part  IV.,  an 
earning  ability  E'  =  60.09T.  " 

The  maximum  of  the  acuities  of  vision  are  as  above  Ci  =  0.75 
and  c/  =0.75  to  which  belongs  professionally  the  figure  1,  there- 
fore, the  earning  ability  is  : 

E  =  ^'"^^'  =  L><69:CI97 ^  ^^^^^^^ 

C  max.  J- 

Example  3.  If  the  normal  eye  1  suffers  such  an  injury  that 
there  only  remains  a  visual  acuity  of  ci  =0.50  while  the  other  eye 
2  remains  uninjured  (c3  =  0.60)  the  modified  acuities  of  vision  are: 

,  Ci  0.30 

Ci  =  n  —  =  0.75  ^r-^^  =  0.30, 
ni  U,75 

,  c.  ^^0.60 

c>  =:  n  =  0.  <  o  ^  ^„  =  0.75. 
Ho  O.dO 

According  to  table  Y.,  part  lY.,  the  acuities  of  vision  Ci  =^  0.50 
and  02  =  0.60,  for  the  earning  ability  E'  =:  T2.02  and  because 
Cmax.  =  C2=:0.60,  c' ,„a.x  :=  C-/  =  0.75  arc  figures  to  be  replaced  by 
0.75  and  1,  which  is  (see  tal)le)  the  looked-for  earning  ability: 

^       c',n.x.  E'      1X72.02      _„_ 
E= =       ,^  ^.     =  96.02  (. 

Cmax.  0.  / 1) 

Example  4.  If  the  normal  eye  1  l^ecomes  totally  blind  (ci  =  0) 
and  the  other  remains  uninjured  (c>  =  0.60)  the  modified  visual 
acuities  are: 

Ci   =  n       =0.  (t»„^^=0. 
Hi  O./o 

c.        .„.0.60      „„_ 
Ci  =  n       =  0.  /  0 ,.  ^.,  =  0.7o. 
nj  0 .60 

whose  maximum   is  c-/=O.To.  while  C2=0. 60  represents  the  maxi- 
mum of  the  real  visual  acuities.     In  table  Y.,  part  lY.,  we  find  as 
belonging  to  ci=0  and  c-,.=  0.60   an  earning  ability  E':=48.925. 
so  that  according  to  table  on  p.  42  the  figures  1  and  0.7o  b?long 
to  0.75  and  O.GO  the  earning  abilitv  is: 

J,  _  C  „„.  EJ^lX  48.925  _g.  233 

Cmax.  O.^O 


EXAMPLES.  81 

Example  5.  If  both  eyes  suffer  injuries  and  in  1  there  remains 
only  a  visual  acuity  Ci  =  0.-t5,  on  the  other  2  only  Ca^0.40,  the 
modified  acuities  are : 

Ci  0  45 

c,        ^^_0.40       „.^^ 
c/  =  n       =  0.  ( o  „  7.,,  =  O.oO. 
n-;  0.60 

Cmax.  =  Ci=  0.45  and  c'  max.  =^  c/  =0.50  are  figures  which  correspond 
(see  table,  p.  4'?).  with  the  values  0.50  and  0.5833  to  Ci  and  C2. 
According  to  table  V..  jiart  IV.,  there  belongs  an  earning  ability 
E'  =  46.284,  the  final  result  is: 

^        c'  „,ax.  E'       0.583....46.248       ..^  ^_^ 

C  max.  O.oO 


§28.     Group  II.     Both  Eyes  are  Originallij  EqifaUij  Weal--Sighted. 

In  the  following  cases  we  will  suppose  that  the  trade  has  only 
small  ocular  requirements  (n=U.50)  and  that  the  workman  origi- 
nally possessed  visual  acuity  of  only  ni^nj=  0.40  in  both  eyes. 

Example  1.  If  eye  1  be  uninjured  (ci^0.40)  and  the  other 
suffers  an  impairment  to  about  c>  =  0.20,  the  modified  visual  acui- 
ties would  be  according  to  the  following  formula: 

,  Ci  0.40 

Ci'  =  n       =  O.oO  .,  . „  =0.oO. 
ni  0.40 

c/=  n  ^'  =  0.50^^=0.25. 
n,.  0.40 

of  which  the  maximum  isc'„,a.x.  =Ci'  =  0.50,  while  the  real  acuities 
are  Cmax.  =   Ci=  0.40.     According  to  tal)le  VI..  part  IV..  Cj  and  c. 

E'  =  73.338. 
and  as  the  \alues  according  to  tal)le.  p.  42.  correspond  to  the  figures 
1  and  O.TTT  •  •  •  .  the  resulting  earning  ability  is: 

g  __  c  max.  E   ^  1  X  73^38  __  „  .  2Q2 

Cmax.  0.777    .... 

Example  2.  If  one  eye  be  totally  l)lind  (c>=  0)  while  the 
other  be  uninjured  (ci=  0.40).  the  modified  acuities  are  as  follows: 

c/  =  n  ^'  =0.50^4^=0-50. 
Hi  0.40 

c/  =  n  ^'  =  0.50^^,^=  0. 
n<  0.40 


82  EXAMPLES. 


as  above,  Cmax.  =  Ci=  0.40  and  c'max  c  =  0.50;  table  VI.,  part  IV., 
gives  as  belonging  to  ciaiid  c--,  E'  =  54.538,  and  as  a  Avorking  valu- 
ation we  get  for  the  earning  ability : 

^  _  c'„ax.  X  E  _  IX  54.538       „  ,  ^ 

Cmax.  0.777      .     .     . 

Example  3.  If  both  eyes  suffer  the  same  injury  so  that  there 
only  remains  a  visual  acuity  of  Ci  =  C2=0.20  then  the  modified 
acuities  develop  as  follows : 

c/  =  c./  n  ^  -  =  n  ^-  =  0.50  ^^  =  0.25. 
ni  Vii  0.40 

in  which  equation  Cmax.=  Ci=C2=0.20  and  c'max=Ci'  =  c/=  0.25,  to 
which  figures  belong  the  working  values  of  0.333  .  .  and  0.4444  .  .  . 
For  ci  and  C2  ,  table  VI.,  part  IV.,  we  find  an  earning  ability  of 
E  =  29.865,  from  Avhich  we  find  the  real  earning  ability: 

^       c^n.ax.  E^      0.444 29.865  _  „„  ^^ 

Cmax.  \J.666   .   .    . 

Example  4.  If  the  injuries  in  both  eyes  are  different,  the  re- 
sulting acuity  of  ci=  0.20  and  of  ca  =  0.30  we  find  that  the  modi- 
fied acuities  of  vision  Cmax.=  c^  =0.30.  wdiich  are  professionally 
0.555  .  .  .  (p.  42),  the  calculation  for  the  modified  vision  would  b?: 

c/ =  n  ''=  0.50  J^-^!^=  0.25. 
ni  0.40 

/  C2  „0.30      c\^n- 

c>  =  n       =  0.50  „  . ,.  =  0.3  /o. 
n2  0.40 

in  which  the  luaximum  isc'max.  =  C2  =  0.375;  and  as  this  figure  is 
exactly  between  0.40  and  0.35,  the  middle  value  of  the  professional 
quantities  0.777  .  .  .  and  0.666  .  .  .  ,  i.  e.,  0.7222  will  correspond. 
To  Ci  and  C2  belongs  E'  =   51.228,  the  earning  ability  is: 

E  =  ?:=H_E' ^  0,722^. .  .  .  51.228 ^  gg  -gg 

Cmax.  0.555  .... 


§29.     Group  III.     Both  Ei/cs   of  ike  Individual  are   Originally 
Weak-Sighted  to  a  Different  Degree. 

In  the  following  cases  we  deal  with  workingmen  whose  profes- 
sions have  liigh  visual  requirements  (n=0.75)  but  who  have  origi- 
nal visual  acuity  in  one  eye  n  i=0.65  and  in  the  other  n2  =  0.55. 


exa:mples.  83 


c/- 

■-  n 

X 

Ci 

ni 

c/  = 

n 

X 

no 

Example  1.  Eye  1  is  uninjured  (ci  =  0.6o)  while  the  visual 
acuity  in  the  other  has  been  impaired  by  injury  to  0,,=^  0.20,  the 
modified  acuities  are: 

,, ^  ^0.65        „  r-r 

o.<  0x^-^  =  0.75. 

U.bo 

0.75  X^??  =  0.27. 
0.00 

the  maximum  c'„iax.=  Ci'=0.T5,while  we  get  for  the  maximiim  of  the 
real  acuities  Cniax.=  Ci^  0.05.  The  first  vahie  should  be  replaced 
professionally  by  1  according  to  the  table  on  p.  43 ;  the  second  by 
0.833  ...  To  Ci  andc2,  table  T.,  part  IV.,  furnish  us  the  quantity 
E':^  77.079,  the  earning  ability  is  therefore: 

Cmax.  0.8334.  ,  .  . 

Example  2.  If  one  eye  becomes  totally  blind  (c2=  0)  while 
the  other  remains  uninjured  (ci=0.65),  the  modified  acuities  are: 

c/  =  n  X  ^'  =  0.75  X  ^  =  0.75. 

c./  =  n  X  ^'  =  0.75  X  ^  =  0. 

Cmax.=  Ci^  0.65  andc'max.=  Ci'^  0.75;  table  Y.,part  IV.,  shows  for 
Ci  and  C2,  E'  =  55.519,  the  professional  values  are  the  same  as  in 
the  former  example ;  the  earning  ability  is : 

T-,  C  max.     -Cj  iX.00.Oiy  ^^  rrto 

Example  3.  If  both  eyes  suffer  injuries  of  which  the  vision 
of  one  eye  is  reduced  to  Ci  =  0.50,  and  in  the  other  to  0^=0.40, 
where  Cmax.=  Ci=0.45  (professionally  Cmax.=  0.50),  the  modified 
acuities  are  according  to  the  following  formula : 

,  ^  Ci       ,-,  ^ ^  0.45      „  -^ 

c/  =  n  X  -  -  =  0. 1  o  X  T^TT.  =  O.o2. 

Di  0.60 

c./  =  n  X  —  =  0.  ( o  X  TT^-  =  0.06. 
T\-i  0.55 

whose  maximum  c'raax.=C2'=0.5<j,  which  professionally  represents 
a  valuation  of  (table  V.)* 

lOOcg'  —  15      100  X  0.56  — 15 


60  60 


=  0.6833, 


•The  profpssional  values  belonging  to  the  scientific  visual  acuities  are  obtained  by  the 
following  formula: 

^      lOOe— 15  ^         „      100c— 5 

Group  I.      — ~^ Group  II. 


60  "^  45 


84  EXAMPLES. 


To  Ci  and  c-j  Ijoloiiii-  according  to  tabic   \'.,  part  IV.,  E  =4:0.24:8, 
from  which  we  deduce  the  earning  ability  of : 

^      c'„,ax.  E       0.6833  ....  46.248       „„  „_ 
E  =  —        =  _^ =63.206. 

Cna.v  0.50 

ExAirPLE  4.  It'  both,  eves  be  injured,  but  in  sucli  a  manner 
tliat  one  becomes  totally  blind  ci^  0,  while  the  other  is  reduced  to 
Ca=0.30,  the  modified  acuities  of  vision  h.ave  the  following  values: 

c/  =  nX"  =0.75X^^^=0. 
ni  0.65 

c/  =  n  X  —  =  0.75  X  [J-|^  =  0.41. 
n-z  0.55 

Cmax.  =C2  =  0.30  (professionalh'  =  0.25)  and  c'max.=C2'=  0.41  (to  be 

,       .  ,     100X0.41  —  15     ",  ,.,.,        X       1       ,    1       •      +  ^ 

replaced  by ~ .r=r0.4o3  .  .  .)  and  as  belonging  to  Cj  and 

02,   we  take  from  table  Y,    part  IX.^  E'  =  13.091,     which  quantity 
allows  us  for  the  ability  to  earn : 

g  ^  c^,„xj'  ^  0.433 13.091  ^  22  691 

Cmax.  U.ZO 


§30.     Group  IV.     In  These  C'ascs  One  Eye  Was  Or'ujinally  Blind 
and  the  0 titer  WeaJc'Sighted. 

We  suppose  that  we  have  to  deal  with  an  individual  whose  pro- 
fession has  only  low  visual  requirements  (n^  0.50).  The  one  eye 
is  totally  blind  (ni=  0)  while  the  other  possesses  a  visual  acuity  of 
n2-=  0.45. 

If  the  seeing  eye  be  injured  and  there  remains  only  a  visual 
acuity  of  C2=0.25,  because  Ci  =  0  has  to  be  used,  there  is  c,„ax.  =C2 
^=0.25 (professionally  =  0.444  .  .  .)and  the  modified  acuity  of  vision 
c/  =  0,  the  maximum  of  both  values  will  be  : 

C2'=n  X  —  =  0.59  X  ^'^l  =  0.28  .  . 
na  0.45 

which  corresponds  professionally  with  the  figures: 
100  X  0.28  —  0.5 


45 


=  0.511 


To  Ci  and  C2  belong  according  to  table  XA'L.  part  IV..  E' =  39.582; 
the  earning  ability  is  therefore : 

^      c,„ax.  E'      0.511  ...  39.582       ,_  ..^ 
E=  =        ^  ...  =  45.019. 

Cmax.  0.444  .  .  . 


LOSS  OF  ONE  EYE.  85 


CHAPTER  XIII. 


THE  LOSS  OF  ONE  EYE  THROUGH  ACCIDENT. 


Claims  for  damages  in  the  case  of  accidental  loss  of  an  eye  are 
•of  frequent  occurrence  and  we  will  therefore  give  this  subject  ex- 
haustive consideration. 

§;j1.     Estimation  of  the  Vision  in  the  Case  of  the  Loss  of  One  Eye. 

In  Chap.  A'l.,  §  11,  p.  ,  we  gave  the  following  professional 
calculation  for  the  binocular  act  of  vision.  Our  object  is  now  to 
estimate  in  what  manner  the  individual  factors  of  the  formula  are 
impaired  in  value  by  the  total  loss  of  one  eye.  The  formula  for  the 
binocular  act  was : 


^,  =  CV?V  (mi  m2  ms  m*  iHo  me)  (m/  m/  ms'  m/  nis'  ms) 
In  the  case  of  the  loss  of  one  eye,  the  central  acuity  (C  of  our 
formula),  is  so  little  affected  that  the  slight  loss  from  the  taking 
away  of  the  vision  in  one  eye  may  be  ignored.  The  clearness  of 
sight  is  just  as  good  in  monocular  vision  as  in  binocular.  Ze- 
hender  (54-,  p.  G28)  says  that  the.  one-eyed  condition  does  not  offer 
any  ohstacles  for  following  a  trade  from  the  visual  point  of  view, 
but  this  expression  should  be  understood  as  only  pertaining  to  the 
visual  acuity  and  not  to  the  other  factors.  "We,  therefore,  put  the 
visual  acuity  in  such  cases  with  the  valuation  of  the  trade. 
Of  course,  we  must  remember  that  diminution  of  the  acuity 
a  little  below  the  scientific  standard  but  not  encroaching  on. the 
trade  limits,  should  not  be  regarded  as  injury  incurring  a  liability, 
for  we  have  shown  in  Chap.  YI.,  §  12,  that  a  visual  acuity  of  0.75 — 
0.50  should  be  regarded  professionally  as  normal.  In  professions 
with  higher  visual  demands,  a  visual  acuity  of  0.75  is  regarded  as 
normal  equals  1,  and  in  trades  with  smaller  demands  a  visual 
acuity  of  0.50  is  regarded  as  normal  equals  1.  If  the  injured  per- 
son liave  a  visual  acuity  of  0.75  or  0.50  we  should  not  immediately 
state  that  his  working  powers  have  sulfV'Vcd  l)ut  sliould  examine  into 
the  visual  requirements  of  his  trade.  If  we  Ijelieve,  that  the  voca- 
tion requires  fine  vision,  we  would  regard  a  visual  acuity  of  0.75 
as  normal.  l)ut  if  the  eye  work  is  less.  0.50  may  be  regarded  as 
normal  or  1. 

The  peripheric  vision  is  but  little  affected  through  the  loss  of 
one  eye.  because  the  extent  of  the  monocular  field  of  vision  is  but 
a  little  narrower  tb.an  that  of  the  ])inocular  field.  Only  one  seg- 
ment is  missing  after  the  loss  of  one  eve.  According  to  our  ar- 
rangement of  the  entire  field  of  vision  into  three  concentric  zones 


86  MUSCLE  VALUES  IN  LOSS  OF   ONE  EYE. 


(})lato  IV.,  Y\g.  1),  the  loss  would  be  one-sixth  of  the  whovc  field 
(eitlicr  the  blue  or  the  red  part  of  the  drawing.)  Therefore,  after 
the  loss  of  one  eye  five-sixths  of  the  field  would  remain  which  Ave 

would  insert  into  the  formula  as   w  —  V 

r  6  • 

The  action  of  the  muscles  will  be  materially  impaired,  because 
estimation  of  distances,  stereoscopic  vision  and  judging  of  dimen- 
sions are  dependent  upon  binocular  vision  and  are  lost  when  it  is 
disturbed,  but  these  functions  are  only  temporally  lost.  A  child 
losing  an  eye  at  an  early  age,  learns  immediately  to  estimate  dis- 
tances, dimensions  and  relations  of  objects;  an  adult  recovers  more 
or  less  of  these  functions,  and  as  a  rule  in  a  very  short  time ;  for  di- 
mensions, distances,  etc.,  are  known  to  him  through  his  former  ex- 
perience Avith  binocular  vision.  The  muscular  sense  becomes  more- 
developed  for  the  remaining  eye,  and  the  estimation  of  distance* 
and  size  of  objects  is  restored.  Although  Moorcn  (29) disregards  that, 
our  OAvn  rather  consideral)le  experience  Avould  alloAV  us  to  relate  of 
numerous  persons  who  finally  had  these  functions  restored  so  that 
they  were  ultimately  able  to  estimate  distances,  the  form  and  the 
relation  of  objects  just  as  well  as  persons  Avith  tAvo  eyes.  Similar 
experiences  have  been  noted  by  other  authors  (Guillery  l-i,  p.  215).. 
Besides  this,  avo  find  enough  one-eyed  persons  in  every  trade  Avho  can 
do  their  duties  as  Avell  as  those  Avho  have  tAvo  eyes.  In  an  examina- 
tion (Xieden,  31),  of  85,000  miners  in  Bochum.  310  one-eyed  per- 
sons Avere  found  Avho  could  folloAv  their  trade  as  Avell  as  the  others.  As 
a  result  of  this  examination  the  management  of  the  mines  in  the 
Bochum  district  does  not  noAV  regard  the  one-eyed  condition  as  an 
obstacle  for  the  mining  trade,  and  one-eyed  persons  are  accepted  as 
miners,  and  those  Avho  lose  an  eye  Avhile  working  arc  alloAved  to  re- 
main. Under  certain  circumstances  an  exceptional  individual  may 
be  found  Avho  does  not  regain  the  functions  in  question  to  a  suffi- 
cient extent,  but  as  a  general  rule  the  muscular  disorders  from  the 
loss  of  one  eye  are  only  temporary,  and  in  figuring  impairment  of 
the  earning  ability  this  should  be  considered.  For  a  time  Ave  may 
giA'e  this  impairment  an  expression  in  our  calculation,  but  it  should 
be  reduced  or  removed  in  calculating  the  latter  conditions.  One- 
year  is  sufficient  liberal  allowance  for  the  individual  to  adapt  his 
monocular  vision  to  the  demands  of  his  profession.  A  re-examina- 
tion and  ncAv  calculation  may  be  made  one  year  afterAvards,  and  the 
parties  interested  in  the  case  should  be  informed  that  the  alloAvance- 
Avould  be  less  after  one  year. 

To  form  the  muscular  action  M  into  an  arithmetical  quantity, 
Ave  divide  it  into  three  separate  functions,  Avhich  Ave  intend  to  regard 
as  of  equal  value;  {.  e.,  1,  into  the  part  for  moving  the  right  eye; 
2,  the  left  eye ;  3,  the  binocular  part.  For  our  purposes  both  eyes 
must  be  regarded  as  of  equal  value.  Wlien  one  eye  becomes  blind,, 
the  tliird  part  used  to  estimate  distances,  etc.,  is  entirely  omitted,. 


MONOCULAR  BLINDNESS  AND  ABILITY  TO  COMPETE.  87 


but  the  other  two  factors  remain,  even  if  one  only  has  to  do  with 
the  movement  of  a  blind  eye  or  of  a  stump,  for  in  the  latter  case 
it  serves  as  a  support  for  an  artificial  eye.  therefore,  the  muscular 
action  remaining  in  the  case  of  loss  of  one  eye  would  be  entered 
into  the  formula  for  the  act  of  vision  as: 


r 


^M. 


The  formula  for  working  vision  in  the  case  of  monocular  blind- 
ness would  be : 


It  should  be  remembered  that  in  professions  with  higher  visual 
demands  the  visual  acuity  C  should  be  regarded  as  1  even  if  it  is 
only  three-fourths  of  the  scientific  standard  and  in  lower  demands  it 
is  considered  as  of  normal  value  if  only  one-half  of  the  scientific 
standard. 

§32.     Estimation   of  the   Ahilifij   to  Coinpctc   after  ttic   Loss   of 
One  Eye. 

In  estimating  the  ability  to  compete  after  the  loss  of  one  eye, 
the  impaired  values  of  the  different  factors  entering  into  the  act 
of  vision  should  be  considered  (Chap.  YIL,  §  15).     The  value  of 


the  visual  field  would  be  1'        P    and  of  the  musclar  action  f--M. 


The  central  acuity,  from  the  professional  standpoint,  is  not  con- 
sidered to  have  suffered,  but  still  there  is  an  impairment  of  the 
earning  ability  (Chap.  YL,  §  11,  p.  33.)  The  formula  for  the 
ability  to  compete  is  taken  as  a  root  value,  as  it  is  of  less  import- 
ance than  the  others,  and  its  exponent  is  made  a  changeable  one, 
to  agree  with  the  seriousness  of  the  ocular  injury,  as  we  have  shown 
in  Chap.  VII. ,  §  15,  p.  48.  "We  will  l)rieffy  refer  to  the^e  condi- 
tions :  The  ability  to  compete  is  dependent  not  only  on  the  condr- 
tion  of  the  ocular  apparatus  of  ihe  particular  individual  but  also, 
and  even  much  more,  upon  the  judgment  of  the  employer.  Accord- 
ing to  the  seriousness  of  the  injury,  the  employer  becomes  more 
rigid,  and  if  one  eye  be  lost  will  even  refuse  work  on  this  account. 
An  employer  may  be  willing  to  employindividuals  with  slight  ocular 
disorders,  but  will  frequently  draw  the  line  with  the  one-eyed.  He 
may  occasionally  employ  a  one-eyed  man  for  roiigh  work,  but  for 
finer  work  will  always  prefer  a  man  with  two  eyes.  There  may  be 
exceptions,  as  there  may  bo  employers  who  regard  one-eyed  individ- 
uals as  able  as  normal  sighted  ones,  but  a  normal  siiihted  one  will 


88  EARXIXG  ABILITY  IX  MOXOCULARISM. 


most  always  Ijo  preferred.     Tliese  eoiulitions  must  not  be  overlooked 
in  order  to  do  justice. 

The  ability  to  compete,  according  to  our  conception,  is  a  proper 
fraction,  because  it  is  a  ])roduct  whose  factors  are  either  proper 
fractions  or  equal  to  1.  If  a  proper  fraction  be  taken  as  a  root  we 
are  able  to  raise  or  diminish  its  value  by  choosing  the  exponent 
of  the  root;  with  a  raising  exponent  the  root  value  enhances,  and 
vice  versa.  If  we  adaj)t  the  ability  to  compete  in  one  case  as  the 
10th  root  and  in  another  as  the  oth  root,  in  the  first  case  the  value 
would  be  greater  and  in  the  latter  smaller.  Thus  by  enhancing  the 
ability  to  compete,  tlic  earning  ability  increases  while  the  other  way 
it  diminishes.  If  in  the  ease  of  slighter  injuries  we  use  the  ex- 
ponent 10;  by  taking  a  smaller  exponent,  for  instance,  o,  to  reduce 
its  own  and  the  value  of  the  earning  ability,  it  would  meet  the  re- 
quirements of  the  loss  of  one  eye  in  those  trades  having  higher 
visual  demands,  whereas  for  coarser  trades  we  may  take  7  as  the 
exponent.  (See  Cha]).  YH.,  S  I-'-  P-  ■+^)-  In  fl^(^  fii'>t  case,  we 
would  get  for  the  ability  to  compete  the  following  expression  : 


r^rii^P^ 


M, 


and  in  the  second  case 


r'f^Wi^i. 


M. 


§33.     Esiliiiafiuii    of    iJte   Edniiiuj   AhlUtij    Where    One   Eye   Be- 
comes Blind . 

X  

According  to  the  formula  for  the  earning  ability  E  =  F  +  V  K. 

I.     In  professions  with  higher  visual  demands  for  the  first  year 
after  the  injury : 


B=-r^r^'r^^7Ff^; 


and  after  the  first  vear: 
E  =  IC 


n^f-fw^Wff, 


FORMULA  FOB  EARNIXG  ABILITY  IJf  MONOCULARISM.  89 


II.     In  professions  with  lesser  visual  demands  I'or  the  first  year 
after  the  injury  : 


--F^r^.rv"yy7y|^ 


and  after  the  first  vear 


E^icf|7fMfiV^«|y7y 


M. 


The  calculation  of  these  formulas  has  been  made,  by  the  as- 
sistance of  our  curves,  so  simple  that  it  is  reduced  almost  to  com- 
mon multiplication.     Let  us  figure  the  first  formula: 


E  = 


^^ij^w^p'r^T^'^ju. 


C  the  ceutral  maximal  visual  acuity  remains  1;   l/-— pmay  be 

read  on  plate  A'  without  difficulty;  as  more  convenient  we  change 
the  fraction  %  into  a  decimal — 0.833,  and    V  0.833  P  according 


to  our  curves  equals  0.913.     V        M  'j^ing'  changed  into  a  decimal 

0.666,  is  found  on  plate  Y.  as  0.004.     The  equation  for  the  ability 
to  compete*  would  thus  be : 

should  be  first  figured  into  its  single  factors  before  we  can  find  the 
total  value  in  plate  III.;  when  we  do  this,  we  get  for  the  central 


acuity     ^-   the  value  equals   0.r)0;     |/  ^     p  =     0.913   aud 

i      

1/2 

w  --  M.  =  0.904.     The  equation  for  the  ability  to  compete  would 

O 

5    _  ^  ___   ___ fi 

thus  be:    K  0.50 X 0.913 X  0.904=  V  0.4127    and  this  figure  we 


yrj   _j_  Q       4 
F    P  r    M     *'^^  factors 

Cj  and    Cg  should  ahvii.v.s  be  replaced  by  their  professional  valuation. 


90  PERCENTAGE  OF  LOSS  IN  MONOCULARISM. 


find  on  plate  V.,  curve  3,  the  valuation  equals  0.838.         We  state 
again  the  original  formula  : 


which  has  been  reduced  to :  1  X  0.913  X  0.838  =  0.69145,  which 
in  percentage  is  69.145  per  cent.,  which  is  the  full  earning  ability 
and  therefore  its  impairment  is  30.855  per  cent.  Should  Ave  have 
worked  this  equation  out  entirely  by  figures,  we  would  have  found 
the  values  69.097  per  cent,  and  30.903  per  cent.,  which  differ  imma- 
terialh"  from  those  given  by  our  curves.  This  example  shows  that 
our  curves  simplify  the  calculation  without  materially  changing 
the  results. 

According  fo  our  calculations  for  trades  with  Irigher  visual  de- 
mands ice  find  that  a  one-eyed  person  after  being  cured  of  the  ocular 
disease  has  an  impairment  of  the  earning  ability  amounting  to 
30.903  per  cent.,  and  after  one  year  of  21.960  per  cent.,  while  for 
vocations  demanding  less  vision  the  values  would  be  21 .315  per  cent, 
and  18.3SS  per  cent.  Of  course,  it  would  be  left  to  the  manage- 
ment of  the  Insurance  Companies  as  well  as  to  the  physician  to 
change  these  proportions  more  or  less  according  to  the  circumstances 
of  the  case.  Approximately  we  may  say  that  a  one-eyed  person  has 
lost  30  per  cent,  of  his  earning  ability  for  the  first  year  after  the 
accident  and  20  per  cent,  afterwards  for  the  higher  class  of  trades 
and  for  the  lower  class  the  proportion  would  be  21  per  cent,  for  the 
first  year  and  IS  per  cent,  thereafter.  Certainly  there  is  a  difference 
between  the  individual  who  has  been  employed  in  fine  handiwork 
and  one  doing  common  manual  labor,  and  justice  demands  that  a 
difference  should  be  made  in  judging  the  indemnity.  The  system 
in  vogue  was  an  unfair  one,  as  it  over-estimated  the  valuation  for  the 
loss  of  one  eye,  the  Imperial  Insurance  Office  (3)  having  given 
33  1-3  per  cent,  indemnity.  Heddiius  (18)  had  fixed  the  indemnity 
at  25  per  cent.;  Groenouw  (12)  accepts  the  sliding  scale  as  made 
by  Magnus,  his  values  fluctuating  between  20  and  30  per  cent.,  and 
are  therefore  very  close  to  the  indemnity  proposed  by  Magnus ;  but 
they  must  be  regarded  solely  as  arbitrary  estimations  and  not  the 
result  of  exact  calculations  as  have  been  given  in  this  book.  Ex- 
amination of  all  one-eyed  persons  in  the  iron  and  steel  trades  in 
certain  districts  in  Germany  showed  that  there  was  an  actual  im- 
pairment in  the  amount  of  work  done  and  the  wages  earned  of  26 
per  cent,  at  the  highest  (Magnus,  26).  Examination  of  the  Miners' 
Association  in  Halle  a.  S.  (41)  showed  only  20  per  cent. 

All  these  facts  speak  for  a  revision  of  the  33  1-3  per  cent,  rate 
now  granted  by  the  German  Insurance  offices.  No  real  difference 
should  be  made  for  the  values  of  the  right  or  the  left  eye,  although 
it  is  shown  that  the  left  eye  is  injured  much  more  frequently  (Ot- 


GRADUAL  LOSS  OF  SIGHT  IX  OXE  EYE.  9] 


linger  33,  p.  TO)  ;  the  left  eye  being  injured  in  60.2  per  cent  and 
the  right  in  39.8  per  cent.  It  would  be  perhaps  well  for  the  work- 
jnan  after  losing  the  less  endangered  right  eye  to  avoid  vocations  in 
which  injuries  to  the  eye  are  frequent. 

Our  valuations  of  30.903  per  cent,  and  2T.315  per  cent,  admit 
after  one  year  of  a  reduction,  because  those  muscular  functions 
whicli  were  formerly  executed  by  both  eyes  are  partly  or  entirely  re- 
stored. The  iigures  of  21.97  per  cent,  or  18.39  per  cent,  should  be 
regarded  as  the  maximal  limit  to  which  the  damage  may  be  reduced. 
This  reduction  should  not  be  obligatory  in  every  case  but  the  in- 
dividnal  should  receive  full  consideration.  In  the  case  of  older 
men,  a  reduction  may  perhaps  never  be  made  because  an  old  man 
will  never  acquire  new  functions  as  will  the  younger  one.  The  in- 
telligence of  the  person  is  a  factor  and  the  profession  itself  should 
play  a  role  as  regards  this  reduction  of  damage,  depending  upon 
the  visual  demands  of  the  vocation.  In  the  case  of  smaller  ocular 
demands  we  need  not  be  so  considerate. 

A  further  important  question  is  whether  the  sudden  total  loss  of 
one  eye  does  not  demand  a  different  valuation  for  the  earning  ability 
than  gradual  growing  blindness  on  one  side.  Accidental  blindness 
may  be  caused  in  different  ways;  either  the  eye  may  be  injured  to 
such  an  extent  that  sight  is  immediately  lost  or  the  injury  produces 
a  diseased  condition  leading  gradually  to  the  loss  of  vision.  There 
are  numerous  cases  in  which  passable  visual  acuity  exists  for  some 
time  after  the  accident  and  blindness  only  develops  after  several 
years.  Such  cases  occur  from  blows  upon  the  head  causing  rupture 
of  the  posterior  coats  of  the  eye,  causing  ultimate  detachment  of 
the  retina  through  cicatricial  contraction.  Iron  and  copper  splin- 
ters in  the  interior  of  the  eye  may,  after  one  or  two  years,  cause 
))lindness.  Sudden  blindness  in  one  eye  has  certain  ocular  conse- 
(|uences  which  make  the  following  of  the  profession  more  difficult 
for  the  injured,  /.  e.,  the  judgment  of  distances,  etc.,  and  should  be 
considered  in  estimating  the  impairment  of  the  earning  ability.  If 
the  one-sided  blindness  develops  gradually,  the  lapse  of  time  per- 
mits the  injured  person  to  adapt  himself  to  the  ocular  consequences 
of  being  one-eyed.  It  is,  therefore,  not  more  than  fair  to  consider 
these  conditions  in  figuring  the  impairment  of  the  earning  ability. 
We  would,  therefore,  figure  the  impairment  of  the  earning  ability  in 
:i  case  of  gradual  loss  of  sight  at  the  lower  rates  above  given.  There- 
fore the  {mpainiient  of  the  earning  ahlliti/  from  the  gradual  loss 
of  the  ^ight  in  one  eye  following  an  accident  in  trades  of  higher 
risval  demands  is  21.97  per  cent.,  in  professions  icith  lower  visual 
demands  18.39  per  cent. 

There  Avas  a  time  when  50  per  cent,  was  regarded  as  the  valu- 
ation for  the  loss  of  one  eye  (Mooren  29;  Golebiewski  10,  pp.  129 
and  241).  But  this  is  only  a  matter  of  history,  for  when  the  sub- 
ject of  economic  damage  from  the  loss  of  one  eye  was  first  preached, 
the  valuation  of  the   two  eyes  was   placed   at   100,   and   one-half 


92  DANGER  OF  BLINDNESS   IN  MONOCULAHI.S:\r. 

or  50  per  cent,  taken  off  for  one  eye.  There  was  no  scler.- 
tific  ophthalmologic  investigation  of  the  question,  and  it  was 
believed  that  the  factors  for  fixing  the  amount  of  an- 
nuity or  damage  sliould  be  looked  for  mainly  in  the 
philanthropic-philosophical  and  not  in  the  ophthalmologic  pro- 
fessional sphere.  Zeliender's  (.53)  33  1-3  per  cent,  and  Jatzow's 
(19a)  40  per  cent,  are  estimations  ))ased  upon  psychic  factors.  The 
executive  boards  of  the  insurance  offices  and  societies  generally  pre- 
fer a  much  lower  indemnity  (Moses  30,  p.  23).  It  is  very  likely 
that  the  present  33  1-3  per  cent,  rate  will  share  the  fate  of  the  50 
per  cent,  rate  and  soon  will  be  replaced  by  a  scientific  standard  such 
as  we  have  given  it.  Our  methods  are  based  upon  scientific  principles 
and  give  the  workingman  of  all  classes  pro  rata  indemnity  corre- 
sponding to  the  amount  of  the  damage  to  their  working  powers. 
The  employer  certainly  finds  in  our  system  a  protection  against  un- 
fair claims  of  the  employed.  The  badly  injured  person  is  really 
better  off  under  our  S3'stem,  for  our  "total  disability  of  earning"  be- 
gins with  a  visual  acuity  of  below  one-seventh  to  one-twentieth, 
whereas  the  old  system  total  disal)ility  was  when  the  vision  was 
under  one-hundredth.  It  is,  therefore,  just  and  fair  for  both  em- 
ployer and  employed. 

§34.  Conccrninr/  the  Supposed  Greater  Danger  of  a  One-Eyed 
Person  Becoming  Totally  Blind  and  Its  Relations  to  In- 
demnity. 

Perhaps  the  reader,  in  our  calculation  of  the  impairment  to 
the  earning  al)ility,  may  have  already  missed  any  reference  or  con- 
sideration of  the  ultimate  blindness  or  of  the  greater  danger  of  be- 
coming blind  for  the  one-eyed  person,  upon  which  has  been  laid 
such  stress  by  Zehender  (53,  p.  269).  We  do  not  consider,  as  he 
does,  that  this  danger  under  all  circumstances  is  double  that  of  the 
normal  person,  for  the  risk  is  but  little  greater.  For  instance,  the 
most  frequent  cause  of  blindness  1)etween  the  ages  of  15  and  45 
years  is  atrophy  of  the  optic  nerve  (Magnus  24,  p.  24G)  and  from 
45  to  60  it  is  glaucoma;  but  we  must  remember  that  it  is  the  gen- 
eral rule  for  atrophy  of  the  nerve  to  be  double-sided.  The  causes 
of  one-sided  atrophy  are  very  rare  and  are  very  different  patho- 
logically from  the  binocular  ones.  There  is  precisely  the  same  dan- 
ger from  this  disease.  Zehender's  philantrophic  feeling  brought 
him  in  glaring  antagonism  to  statistics.  All  he  should  have  said 
was,  that  the  possilnlity  of  becoming  blind  in  certain  diseases  and 
especially  in  certain  injuries  of  the  eyes  is  greater  in  the  one-eyed 
person,  for,  when  the  normal  human  being  loses  one  of  his  eyes  by 
an  accident,  he.  of  course,  retains  the  sight  of  the  other,  Avhile  the 
one-eyed  person  in  losing  his  one  eye  becomes  totally  blind.  Theo- 
retically there  is  nothing  to  be  said  against  this  conclusion,  but  prac- 
tically it  is  not  of  much  importance.  Our  experiences  show  that 
but  few  one-eyed  persons  lose  their  other  eye  through  an  injury 


DANGER  OIT  TOTAL  BLINDNESS.  93 


and,  at  an}-  rate,  these  are  so  few  that  there  is  certainly  not  double 
the  danger  of  becoming  blind.  Magnus  {2-iL,  p.  184)  states  that 
only  once  within  the  last  eight  years  has  he  seen  a  one-eyed  person 
whose  sound  eye  was  injured  by  an  injury ;  a  fact  Avhich  is  surpris- 
ing in  view  of  the  numerous  losses  of  one  eye  of  normal-siglited. 
Wiirdemann,  practicing  in  a  manufacturing  district  where  ocular 
accidents  are  common,  has  seen  but  two  eases  of  the  loss  of  the  re- 
maining eye  of  a  one-eyed  person  by  accident  within  the  last  ten 
years.  The  general  experience  of  other  practitioners  will  surely 
support  the  above  statements.  We  do  not  think  that  this  question 
should  allow  of  additional  indemnification  in  relation  to  fiffuring 
the  accident  insurance  or  the  annuity  to  be  granted  in  any  case  to 
workmen.  Accidents  to  the  remaining  eye  are  more  rare  than  to 
persons  who  have  two  eyes,  for  in  the  first  place  they  have  learned  to 
be  particularly  careful  to  shield  the  remaining  eye  from  injury  and 
to  use  it  properly.  We  know  one-eyed  persons  in  many  vocations, 
in  some  of  which  the  liability  to  ocular  accidents  is  frequent,  for  in- 
stance, workmen  in  stone  quarries,  in  mines,  in  machine  shops,  etc., 
but  we  have  never  heard  from  any  one  that  the  concern  about  his  one 
eye  hindered  him  in  his  profession.  Complaints  of  one-eyed  per- 
sons are  generally  quite  different  and  refer  to  disorders  in  judging 
distances,  etc.;  often  such  persons,  who  try  to  exaggerate  their  in- 
jury, use  other  means  than  the  concern  regarding  their  remaining 
eye.  We  must,  therefore,  exclude  the  danger  of  becoming  blind 
under  all  circumstances;  in  calculating  the  impairment  of  the  earn- 
ing ability  of  the  one-eyed  person  the  question  of  sympathetic  in- 
flammation should  be  considered  from  the  same  point  of  view,  but 
this  is  so  important  that  wo  will  treat  it  in  a  separate  chapter. 
(Chap.  XVI.) 


94  INJURIES  TO  LENS. 


CHAPTER  XIV. 


§35.     Accidental  hijuries  of  the  Crystalline  Lens.     Aphal-ia. 

Tn  injuries  of  the  crvstallirie  lens  we  have  the  peculiar  condition 
that  as  long  as  the  injiin-  lasts  and  the  opaque  lens  stops  the  fur.c- 
tiou  of  siffht.  there  is  no  doubt  regarding  the  extent  of  the  impair- 
ment to  the  earning  ability,  but  as*  soon  as  the  injured  lens  is 
taken  out  by  an  operation  which  clears  the  pupil  and  vision  returns, 
then  difficulties  appear  in  the  calculation.  We  have  had  occasion  to 
s-tudy  many  opinions  and  decisions  in  order  to  make  satisfactory 
judgment  of  the  results  of  aphakia,  upon  the  Avorking  powers.  If 
one  eye  be  normal  and  the  other  became  aphakic  through  the  loss  O'f 
the  lens,  the  unequal  refraction  of  both  eyes  renders  the  vision  prac- 
tically monocular,  as  the  lensless  eye  is  so  hyperopic  that  a  concert 
of  action  of  both  eyes  for  professional  use  cannot  be  had;  even 
though  the  refraction  be  neutralized  by  convex  glasses  it  cannot 
work  together  with  the  sound  eye.  and  the  subject  will  always  pre- 
fer to  dispense  with  the  visual  acuity  on  the  lenseless  side  and  work 
with  the  normal  eye.  We,  therefore,  as  long  as  the  other  eye  re- 
mains sound,  regard  one-sided  aphakia  in  the  same  manner  as  that 
of  an  individual  having  suffered  important  injuries  to  the  visual 
acuity  Avhile  the  visual  field  and  the  muscles  remain  normal.  This 
assertion  cannot  be  changed  by  the  fact  that  eventually  the  visual 
acuity  of  the  aphakic  eye  mav  be  one-half  or  more;  for  if  the  in- 
dividual cannot  make  use  of  this  acquired  acuity  of  vision  in  the  in- 
jured eye.  his  success  in  earning  remains  exactly  the  same  as  if  the 
visual  acuity  were  not  sufficient  for  use.  Therefore  we  put  mo- 
nocular aphakia  in  the  same  position  as  the  eye  whose  central  acuity 
is  impaired  to  a  high  degree  and  reduced  to  0.15  in  professions  with 
higher,  and  to  0.05  in  professions  with  lower  ocular  demands.  But 
we  do  not  consider  such  an  eye  in  the  same  relation  as  one  which  is 
blind,  for  it  forms,  as  Fuchs  says  (8a),  "A  reserve  for  the  future." 
But  if  the  operative  removal  of  the  lens  had  not  given  a  satisfactory 
result  regarding  regaining  good  vision,  such  an  aphakic  eye  would 
not  represent  a  prospective  reserve  for  the  future  and  should  be  con- 
sidered as  professionally  blind.  Thus  the  valuation  of  the  relations 
of  the  aphakic  eye  to  the  earning  ability  may  be  made  upon  sound 
principles  and  with  due  regard  to  the  individual  peculiarities  of  the 
ease.  Tables  T.  and  A^I.  of  part  lY.  give  information  regarding 
the  impairment  of  the  earning  ability  in  the  case  of  one-sided 
aphakia.  The  conditions  are  as  follows :  If  an  aphakic  eye  has  a 
visual  acuity  of  0.15  and  over,  in  professions  with  higher  visual  de- 
mands, and  of  0.05  and  over,  in  professions  with  lower  visual  de- 
mands, and  if  the  other  eye  remains  normal,  the  impairment  to  the 
earning  ability  would  be  6.G9  per  cent.     But  if  the  aphakic  eye  has  a 


APHAKIA.  95 

visual  acuity  below  0.15  or  0.05,  depending  upon  the  character  of 
the  vocation,  tlie  impairment  of  the  earninu-  ability  would  be  in  the 
first  case  21.9  per  cent,  and  in  the  latter  ca.se  18.3  per  cent  (tables 
v.,  and  yi..  part  IV.)  These  figures  may  be  reduced  to  15.5  per 
cent.,  depending  upon  individual  circumstances.  For  instance,  if 
the  injured  person  is  young  and  gets  along  easily  with  the  changed 
ocular  conditions,  the  lower  figure  may  be  chosen ;  the  employment 
of  the  injured  person,  his  mental  capacity  and  other  factors  will 
play  a  role  in  choosing  the  higlier  or  the  lower  figures.  These  are 
all  conditions  which  should  be  considered  in  every  case  and  left  to 
the  decision  of  the  trade  boards  or  the  physicians.  The  foregoing 
refers  to  cases  Avhere  one  eye  remains  sound;  but  if  a  man  loses  a 
lens  and  the  uninjured  eye  was  previously  weak-sighted,  the  con- 
ditions are  certainly  different.  If  the  uninjured  eye  cannot  be  used 
for  working  purposes,  tiie  aphakic  eye  has  to  be  estimated  as  if  the 
individual  had  been  one-eyed.  We  here  start  from  the  fact  that 
the  impairment  of  the  earning  ability  is  determined  bv  the  central 
acuity  of  vision  Avhich  the  aphakic  eve  has  regained.  If  the  origi- 
nally weak-sighted  and  uninjured  eye  is  still  able  to  earn,  we  have 
to  regard,  in  the  professional  estinuition,  the  extent  of  the  central 
acuity  which  both  eyes  possess.  The  eye  whicli  is  used  and  which 
possesses  the  higliest  degree  of  acuity  must  be  regarded  as  nio-t 
fitted  for  earning  while  the  other  should  be  regarded  as  excluded 
from  work  on  account  of  the  difference  in  the  refraction  ;  the  calcu- 
lation is  then  made  according  to  the  principles  put  down  in  Chan- 
ter XII. 

There  are  still  cases  possilde,  and  we  know  of  such,  in  whicli  an 
individual  who  became  aphakic  on  one  eye  through  an  accident  lias 
later  lost  the  remaining  eye  through  another  accident.  The  calcu- 
lation of  the  impairment  of  the  earning  aliility  would  then  have 
to  start  from  the  central  acuity  of  vision  of  the  aphakic  eye 
which  is  fully  explained  in  tables  Y.  and  VI. 


96  IXJUKIES   TO  EYELIDS,  ETC. 


CHAPTER  XV. 


§3G.     Injuries  of  the  Eyelids,  Conjunctiva  and  Cornea. 

Traiiniatisms  of  the  eyelids^  eoujimctiva  and  cornea  may  hinder 
vision  and  their  inflnence  may  he  measured  by  the  diminution  of 
the  central  acuity  and  the  other  factors  of  the  visual  act.  We  have 
shown  how  burns  may  lead  to  extensive  symblepharou  and  hinder 
the  ocular  movements.  In  one  case  Magnus  notes  where  the  symble- 
pharon  was  entirely  relieved  by  operation,  the  eyelid  remained  thick- 
ened, reddened  and  without  eyelashes  and  the  conjunctiva  was  read- 
ily irritated.  The  disfigurement  of  the  lower  lid  was  such  that  the 
patient  could  only  get  new  work  with  difficulty  and  when  he  obtained 
a  job  would  soon  have  to  give  it  up  again,  as  the  least  irritation 
produced  a  flow  of  tears  which  made  continuation  of  work  impos- 
sible. Xotwithstanding  that  he  had  almost  normal  visual  acuity 
he  had  to  be  regarded  as  imj)aired  for  work.  The  valuation  of  such 
a  case  had  to  be  left  entirely  to  the  physician.  We  would  here 
warn  against  over-estimation  of  disfigurements ;  it  frequently  hap- 
pens that  persons  who  hare  lost  one  eye  by  a  serious  accident  are  not 
satisfied  with  the  annuity,  indemnity  or  amount  of  insurance  that 
has  been  paid  them  and  on  account  of  disfigurement  may  claim  a 
higher  rate,  which  in  certain  cases  has  been  given  to  them.  Mag- 
nus does  not  consider  such  a  course  justifiable,  for  by  his  method 
in  the  valuation  of  the  loss  of  one  eye,  the  disfigurement  connected 
therewith  is  already  considered.  We  have  done  this  in  our  previous 
pages  by  giving  the  proper  valuation  in  such  cases  to  the  ability  to 
compete. 


DANGER  OF  SYMPATHETIC  0PHTHAL:MITIS.  97 


CHAPTER   XVI. 


§37.     Should  the  Danger  of  Si/ in  pathetic  Ophthalmitis  he  Consid" 
crcd  in  Estimating  the  Impairment  of  the  Earning  Ability'? 

The  possibility  of  resultant  sympathetic  disease  in  the  uuiniured 
eye  has  been  brought  up  many  times  in  medical  and  trade  assembly 
circles  and  in  the  law  courts  in  estimating  the  impairment  of  the 
earning  ability.  A  number  of  authorities  have  considered  that  this 
factor  was  of  considerable  moment  in  allowing  an  increase  of  the 
rating;  especially  if  there  is  a  foreign  body  in  the  eye  there  is 
even  a  disposition  to  give  these  conditions  an  expression  in  the 
amount  of  the  rating.  We  do  not  think  that  this  danger  should 
influence  the  amount  of  the  impairment  allowed  of  the  earning 
ability.  The  possibility  of  being  insured  against  sympathetic  in- 
flammation should  be  undertaken  by  the  laborer  himself,  the  same 
as  one  pays  a  premium  for  fire  insurance,  if  it  is  to  be  considered 
at  all.  Such  a  relation  between  the  employer  and  the  employed 
cannot  be  thought  of;  but  if  there  was  positive  danger  of  future 
sympathetic  inflammation  it  might  possibly  be  considered  in  calcu- 
lating the  impairment  to  the  earning  ability,  if  it  really  exerts  a 
hindering  influence  upon  the  workman's  powers ;  for  instance,  if  the 
man  has  to  be  exceedingly  careful  not  to  heighten  that  danger  or  to 
hasten  the  outbreak  of  inflammation  and  thus  has  to  limit  the 
amount  of  work  or  his  working  hours,  an  addition  to  his  annuity 
or  indemnification  might  be  justifiable  and  these  conditions  should 
be  considered.  But  the  factors  which  affect  the  outbreak  of  sympa- 
thetic ophthalmitis  are  not  to  be  looked  for  in  the  performance  of 
the  work  and  are  not  favored  through  the  uses  of  the  eye  connected 
with  working  life.  This  has  been  shown  by  experience.  The  youth- 
ful eye  which  has  not  been  used  very  much  in  working  seems  to  Be 
more  exposed  to  sympathetic  ophthalmia  than  the  older  eye.  The 
danger  of  sympathetic  ophthalmitis  is  greatest  in  the  first  few 
months  after  the  injury  of  the  other  eye.  and  then  it  materially 
diminishes.  From  the  oculist's  standpoint,  the  danger  of  sympa- 
thetic ophthalmitis  cannot  be  regarded  as  limiting  the  earning 
ability,  for  this  danger  may  be  entirely  removed  if  the  patient  sub- 
mits to  the  operation  proposed  by  the  physician. 


98  ]NJl'I!I1;.S  of  the  COIiXEA. 

CHAPTER   XVIL 


§38.     Injuries:  of  the  Conica  ThroiKjh  Splinters  of  Iron  or  Foreign 
Bodies. 

Injury  to  the  cornea  through  splinters  of  iron  or  emery  is  per- 
haps the  most  common  accident.  Special  ditficulties  are  not  found  in 
applying  our  rules  to  such  conditions.  !Most  frequently  the  cornea 
is  injured  hy  snuill  particles  of  metal,  and  such  cases  arc  common 
in  every  oculist's  practice  and  are  of  daily  occurrence  in  ophthal- 
mologic clinics.  As  a  rule  cases  are  immediately  cured  after  re- 
moval of  the  foreign  hody  and  the  little  scars  left  are  too  insig- 
nificant to  exercise  a  detrimental  influence  upon  the  visual  acuity. 
Of  course,  many  such  accidents  may  have  occurred  and  the  cornea 
be  spotted  with  such  small  cicatrices,  but  in  the  course  of  time  the 
"workingman  usually  adapts  himself  to  the  increasing  loss  of  vision 
and  does  not  feel  the  loss  professionally.  There  are  only  excep- 
tional cases  that  might  be  hindered  in  work  by  such  accidents,  and 
the  results  are  best  estimated  l)y  the  rules  pertaining  to  the  esti- 
mation of  the  visual  acuitv. 


IMPAIRMENTS  OF  ACCOMMODATION.  99 

CHAPTER   XVIII. 

§39.     Accidental  hiipainnoits  of  the  Acconnnodation. 

Loss  of  accommodation  without  other  injuries  of  the  eyes  are 
very  seldom  caused  by  an  accident.  They  mostly  develop  from 
serious  contusions  of  the  head,  especially  of  the  forehead,  contusions 
of  the  iris,  etc.,  and  are  much  more  frequently  one-sided  than 
double-sided.  They  may  exist  without  changes  of  the  pupil,  but 
usually  there  is  mydriasis.  Such  injuries  should  not  be  allowed 
lasting  pecuniary  compensation,  because  we  are  always  able  to 
replace  the  lost  accommodation  by  litting  convex  lenses ;  and  as  the 
accident  insurance  law  does  not  indemnify  the  lost  function  itself, 
but  gives  a  pecuniary  compensation  only  when  the  earning  ability 
has  sufFered,  the  impairment  of  the  accommodation  is  surely  not 
within  the  bounds  of  the  accident  insurance  law,  although  claim  for 
small  damages  might  be  allowed.  There  are  conditions  which  are 
in  favor  of  granting  at  least  a  small  indemnity :  for  instance,  if  there 
be  one-sided  paralysis  of  the  accommodation  as  well  as  of  the  pupil, 
thedazzling  and  the  dimness  of  the  images  may  cause  inconvenience; 
but  these  symptoms  ultimately  pass  away,  for  the  sul)Ject  becomes 
used  to  the  condition,  even  though  at  first  he  is  hindered  by  such 
symptoms.  One-sided  paralysis  of  the  accommodation  may  be  reme- 
died bv  the  use  of  convex  glasses;  if  the  injured  person  opposes 
wearing  these,  it  is  his  own  look-out,  for  if  he  throws  away  his 
chance  to  regain  the  lost  function,  by  a  little  inconvenience  like  the 
wearing  of  glasses,  he  should  not  have  a  right  for  an  indemnifica- 
tion based  upon  the  loss  of  earning  ability.  Where  there  is  loss  of 
accommodation,  the  individual  character  of  the  case  should  be  con- 
sidered by  the  physician,  insurance  companies  and  the  courts. 


100  OCULAR  DISEASES. 

CHAPTER   XIX. 


§40.     Common  Diseases  of  ihc  Eyes  of  Local  Oriyln  That  Impair 
ihe  Earning  Power. 

In  addition  to  the  subject  of  injuries  to  the  earning  ability 
caused  by  traumatism,  it  has  been  deemed  well  to  give  a  brief 
resume  of  common  diseases  of  the  eyes  of  local  origin  that  may 
impair  the  earning  power.  In  doing  this  we  quote  largely  from 
Hansen.  (IT) 

Acute  inflammation  of  lids  and  conjunctiva  being  transitory 
seldom  leads  to  more  than  transient  disability.  The  visual  power  is 
decreased  in  proportion  to  their  intensity.  By  reason  of  pain,  swell- 
ing photophobia  and  discharge,  the  patient  has  no  earning  power 
during  their  continuance. 

Chronic  blepharitis  and  conjunctivitis  without  actually  lowering 
the  acuity  of  vision,  prohibit  sustained  near  use  and  cut  down  the 
number  of  daily  working  hours  and  proportionately  the  income. 

Acute  inflauimation  of  the  cornea  of  one  or  both  eyes  totally 
disables. 

Chronic  inflammation  of  the  cornea  of  one  or  both  eyes  totally 
disables. 

Opacities  of  the  cornea  of  one  eye  reduce  the  earning  power  not 
more  than  30  to  ]8  per  cent.  (If  one  eye  be  rendered  entirely 
blind  for  economic  purposes  by  reason  of  corneal  opacity,  it  may  be 
treated  as  a  case  of  monocular  blindness,  the  impairment  of  the 
earning  abilitv  for  which  ranges  between  18  and  30  per  cent.. 
Chap.  XIII.,  §  33,  p.  90.) 

Opacities  of  the  cornea  in  both  e3'es  reduce  th2  earning  power 
according  to  the  visual  acuity. 

Acute  iritis  of  one  or  both  eyes  totally  disables  fnr  periods  of 
six  weeks  or  longer. 

Chronic  iritis  with  posterior  synechia?  reduces  earning  capacity 
according  to  the  visual  acuity,  modified  by  the  number  of  working 
days  or  hours  according  to  the  peculiarities  of  the  case  (50  per 
cent,  by  Hansell). 

Incipient  cataract  of  one  eye,  no  reduction. 

Advancing  cataract  of  both  eyes  reduces  according  to  the  acuity 
of  vision  remaining  and  is  subject  to  continuous  retrogression. 

Complete  cataract  in  both  eyes  completely  disables,  but  after 
successful  operation  on  one  eye  the  case  is  relegated  to  the  catgory 
of  refractive  cases.  The  earning  power  is  restored  according  to 
the  vision  regained  for  far  and  near.  Hansell  cites  a  patient 
operated  upon  for  cataract  who  stated  that  his  earning  power  had 
been  gradually  reduced  from  $18.00  per  week  to  nothing.    For  sir 


OCULAPv  DISEASES.   *  101 

mouths  after  cataract  extraction  his  vision  had  equalkd  20 jc  and 
he  had  earned  $9.00 — 50  per  cent.  loss.  Lately  he  has  vision  with 
a  new  correction  30|xv  and  has  been  able  to  command  his  old 
wages. 

A^itrcous  opacities  of  one  eye  do  not  decrease  the  earning  power, 
nnless  due  to  the  presence  of  a  foreign  body  causing  irritation  and 
photophobia  preventing  full  working  hours,  with  danger  of  sympa- 
thetic ophthalmia. 

Vitreous  opacities  of  both  eyes  decrease  the  earning  power  ac- 
cording to  the  visual  acuity  plus  the  liability  to  total  loss,  which 
juay  be  estimated  at  50  per  cent.  more. 

Detachment  of  the  retina  spontaneously  or  in  myopia  of  one 
eye'may  be  reckoned  as  total  loss  of  that  eye  plus  the  probability 
in  the  latter  of  total  loss  and  total  disability.  Spontaneous  or  idio- 
path.ic  detachment  of  the  retina  of  one  eye  is  rarely  followed  by  a 
similar  affection  in  the  other,  hence  the  probability  of  total  loss  is 
le?s.  'I'he  contrary  pertains,  however,  where  it  follows  as  a  conse- 
quence of  scleral  stretching  and  chorioidal  atrophy  of  myopia,  whtn 
the  earning  power  is  seriously  menaced.  The  choice  of  occupation 
is  rendered  difficult,  since  those  demanding  prolonged  near  use  of 
the  eyes  and  straining  and  stooping  positions  must  be  declined. 

Other  diseases  of  the  retina,  the  result  of  purely  local  causes  and 
limited  to  one  eye,  do  not  decrease  the  earning  power. 

Double  central  retinal  chorioiditis  reduces  the  earning  power  to 
that  of  the  average  laborer,  although  the  periphery  of  the  fields 
may  be  intact.  Exceptions  must  be  made  when  the  earning  power 
depends  upon  intellectual  rather  than  ocular  acuteness. 

Constitutional,  acquired,  or  hereditary  ocular  disease,  such  as 
albuminuric  retinitis,  retinitis  pigmentosa,  tubercular  choroiditis, 
syphilitic  affections  of  the  cornea,  iris,  vitreous  and  fundus  tissues, 
optic  nerve  atroph}',  progressively  reduce  the  earning  power  in 
direct  proportion  to  the  loss  of  vision  until  the  patient's  death  or 
total  disability. 

Congenital  color  blindness  debars  the  individual  from  army, 
navy  and  railroad  service,  but  from  few  practical  pursuits  and  only 
by  limiting  the  selection  of  occupation  does  it  interfere  with  his 
earniug  power.  The  estimate  of  the  degree  is  purely  arbitrary,  but 
probably  does  not  exceed  1  per  cent. 

We  compute  (Chap.  IX..  §  19,  p.  58)  the  loss  of  earning 
power  from  peripheral  limitation  of  the  fields  thus  : 

Loss  of  30  degrees Xo  loss  of  e.  p. 

Loss  of  40  degrees 20  per  cent,  loss  of  e.  p. 

Loss  of  60  degrees 45  per  cent,  loss  of  e.  p. 

Peripheral  limitation  of  one  field  only  entails  loss  of  e.  p.  of 
10  per  cent. 

In  homonymous  hemianopsia Loss  30  per  cent. 

In  bitemporal  hemianopsia Loss  20  per  cent. 

In  binasal  hemianopsia Loss    0  per  cent. 


102  OCTLAR  DISEASES. 

Diplopia  from  monocular  paralysis  irremediable  by  prisms  but 
removed  by  occlusion  of  one  eye  brings  the  patient  into  the  category 
of  the  one-eyed,  but  since  a  variable  amount  of  time  must  elapse 
before  the  individual  is  able  to  resume  his  previous  occupation  and 
to  regain  his  old  skill,  he  suffers  a  loss  during  this  time  of  his  earn- 
ing capacitv  of  18  to  30  per  cent.  (/.  c,  economic  monoculism  is 
produced;  see  Chap.  XIII.,  §  33,  p.  90). 

Paralysis  of  associated  movements  and  double  complete  ophthal- 
]noplegia  externa  completely  disables. 

Errors  of  refraction  deserve  but  scant  attention  in  this  paper, 
since  they  are  for  the  most  part  remediable,  and  the  individual  is 
subjected  to  the  annoyance  only  of  his  dependence  on  spectacles  for 
the  full  nse  of  his  eyes  with  good  vision.  This  is  an  inconvenience, 
but  does  not  decrease  the  earning  power  except  as  applied  to  a  few 
occupations.  In  the  absence  of  disease  persons  with  any  kind  of 
regular  defects  can  be  restored  to  full  earning  power.  In  the  case 
of  an  incorrectil)le  accommodative  and  muscular  trouble  by  which 
an  individual  is  incapacitated  from  the  full  nse  of  his  eyes,  the  loss 
of  earning  power  vrill  equal  the  number  of  hours  daily  that  he  is 
unable  to  work  and  may  be  estimated  at  50  per  cent,  of  his  full 
capacity.  Conical  cornea  and  irregular  astigmatism  not  being  sub- 
ject to  full  correction  by  lenses  diminish  the  earning  ability  accord- 
ing to  the  loss  of  visual  acuity. 

Foreign  bodies  in  the  interior  of  the  eye  totally  incapacitate  for 
a  variable  numlier  of  weeks  and  are  in  the  great  majority  followed 
by  the  loss  of  the  eye.  If  removed  before  the  stage  of  chronic  irri- 
tation sets  in  and  the  danger  of  sympathetic  ophthalmia  is  not  pres- 
ent, the  individual  goes  into  the  list  of  the  one-eyed.  If  allowed 
to  remain  the  earning  power  is  lessened  25  per  cent,  and  in  many 
cases  finally  100  per  cent. 

Foreign  bodies  in  the  cornea  are  readily  removed  usually  with- 
out permanent  cicatrices.  Before  extraction  the  earning  power  is 
reduced  100  per  cent.  The  sudden  loss  of  one  eye  incapacitates  to 
greater  degree  for  a  time  than  the  gradual  loss,  because  the  indi- 
vidual loses  all  judgment  of  space  and  he  requires  time  to  learn 
anew  the  relation  of  objects  to  each  other  and  their  size  and  shape, 
since  the  mental  conceptions  are  changed.  Among  the  trades  that 
require  the  higher  grades  of  vision  the  damage  to  the  earning  power 
in  the  gradual  loss  of  one  eye  is  22  per  cent.,  in  the  lower  18  per 
cent.  Zehender  (54)  says  that  after  the  loss  of  one  eye  only  two- 
thirds  of  the  earning  capacity  remains.  ]\Iooren  (29)  adds  to  this 
the  loss  of  binocular  vision  8  to  IG  per  cent.,  according  to  tlie  dan- 
ger of  the  occupation. 


PART   THIRD. 


Estimation  of  the  Pecuniary  Loss  to  the  Individual  by 
Reason  of  Visual  Imperfections. 


104  WAGES  AND  AGE  OF  W0I!K:\IEN". 


CHAPTER   XX. 


§-il.     Estimation  of  the  Pecuniary  Loss  to  the  Individual  hij  Rea- 
son of  Visual  Imperfections. 

In  the  foregoing  we  have  estimated  the  economic  damage  in  the 
form  of  percentages.  Xow  it  remains  to  apply  these  ratings  to  the 
conditions  met  Avith  in  daily  life. 

Money  being  the  world's  medium  of  exchange  and  of  valuing  a 
man's  work  or  time,  we  must  reduce  the  economic  damage  in  each 
individual  case  to  its  value  in  dollars  and  cents  or  the  monetary 
medium  of  the  country  in  which  the  compensation  for  damage  may 
be  sought.  It  goes  without  saying  that  the  value  of  men's  time  and 
wages  differ  greatly,  not  only  in  different  trades  and  professions, 
but  even  the  various  members  of  the  same  trade  receive  varying 
wages. 

If  we  wish  to  exactly  estimate  the  damage  to  the  individual  case, 
we  must,  therefore,  figure  with  the  compensation  that  the  individual 
himself  has  heen  getting  and  his  probable  future  earnings.  It  must 
bo  allowed  that  this  may  be  done  in  the  case  of  artisans  and  the 
working  classes  generally,  and  that  this  estimate  may  be  legitimately 
used  as  a  basis  with  which  to  calculate  the  pecuniary  loss  he  may 
sustain  by  reason  of  lessened  working  and  earning  ability.  In  the 
case  of  professional  and  business  men,  who  do  not  receive  regular 
wages  or  a  stipulated  income,  it  might  be  considered. strict  justice 
to  the  defendant  to  take  the  average  earnings  of  the  class  to  which 
the  plaintiff  may  belong  as  a  basis  upon  which  to  figure  the  in- 
demnity. 

It  should  be  likewise  considered  that  an  old  man  cannot  lose  (as 
regards  earning  ability)  as  much  as  a  younger  man,  for  the  elder 
has  fewer  prospectiveyearsof  employment  and  consequent  less  money 
equivalent  than  the  younger.  Thus  the  age  of  the  plaintiff  should 
always  be  considered.  It  may  likewise  be  taken  for  granted  that  the 
average  earning  life  begins  at  15  and  ceases  at  65  years ;  that  in  the 
case  of  a  business  or  professional  man  the  wages  will  be  doubled 
every  tenth  year  until  cessation  of  working  life ;  that  in  the  case  of 
working  men  this  doubling  will  occur  for  the  first  two  periods  of 
five  years  and  afterwards  the  usual  rate  will  be  maintained  until  at 
the  age  of  50,  and  15  years  thereafter  though  competition  of  younger 
men  and  natural  infirmities  of  this  period  of  life  then  will  be  a 
certain  reduction  in  the  wages.  Exceptions  to  this  estimate  must 
be  made  in  the  case  of  girls  and  women,  since  their  working  years 
are  fewer  and  their  increase  of  earnings  does  not  follow  the  same 
rule  as' that  of  men;  many,  perhaps  the  majority,  being  employed  in 
shops,  mills  and  offices  and  in  such  positions  that  increase  of  skill 
and  experience  are  not  rewarded  by  increase  of  their  income. 


AGE  SCALE.  105 


Hansell  assumes  (1?)  that  a  professional  or  business  man  will 
double  his  earnings  every  ten  years,  provided  his  mental  and  physi- 
cal health  is  preserved,  and  that  he  has  average  intelligence,  in- 
dustry and  ambition.  He  considers  that  when  the  earning  jwwer 
of  the  individual  falls  below  GG  per  cent,  of  the  average  earning 
capacity,  that  promotion  with  increase  of  income  cannot  be  reckoned 
and  that  when  SO  per  cent,  of  the  visual  power  is  lost  the  man  is 
no  longer  in  a  position  to  earn  the  income  that  was  his  before,  and, 
therefore,  not  onlv  receives  no  increase,  but  his  wages  thereafter 
may  diminish;  and  if  vision  be  reduced  to  counting  fingers  at  1-3  m. 
(Magnus  0.15  to  0.05)  the  loss  is  100  per  cent.,  the  individual 
earning  nothing  and  also  becoming  a  charge  upon  his  family  or  the 
community.  The  doubling  of  the  earnings  for  each  decade  maybe  ap- 
plied as  a  principle  to  most  business  and  professional  men,  but  in  the 
ease  of  laborers  and  artisans,  who  receive  no  promotion  after  having 
attained  a  certain  grade,  it  must  be  modified  in  respect  to  the 
doubling  of  wages  or  income  every  tenth  year.  This  permits  of  a 
decided  simplification  of  the  computation,  for  as  Hansell  says  :  (17) 
if  a  man  earns  $20.00  a  week,  and  will  continue  to  earn  that  amount 
during  the  remainder  of  his  working  years,  his  loss  will  depend 
upon  the  age  at  which  the  incapacity  begins  and  its  degree. 

The  following  table,  which  agrees  roughly  with  the  mathemati- 
cal estimations  of  ^lagnus,  has  been  empirically  figured  by  Hansell : 

Visual  Acuity.  Loss  of  Earning  Capacity. 


^%0 

Y  or  20  per 

cent, 

2«/^0 

Y    "  33 

" 

^5^00 

Y    "  50 

a 

-%60 

Y    "  66 

it 

20/ 
/200 

Y   "  80 

a 

^00 

4.75"  95 

a 

ling  fingers  at  Y  m. 

Y5   "  100 

a 

By  adjusting  Hansell's  age  scale  for  the  pecuniar}'  earnings  to 
the  estimation  of  the  actual  damage  figured  by  the  method  of  Mag- 
nus we  may  arrive  at  an  exact  mathematical  estimation  of  the 
economic  damage  to  the  individual  for  the  loss  of  vision  in  any 
given  case.  In  the  following  tables  we  give  the  earning  power  in 
dollars  and  cents  for  the  five  decades  of  earning  life. 

Table  C  is  adapted  for  the  professional  and  businesss  class 
whose  earnings  as  a  rule  increase  until  their  retirement  from  busi- 
ness. 

Table  D  is  for  the  artisan  classs  whose  earnings  remain  about 
the  same  during  adult  life  and  at  the  end  of  the  working  period 
are  usually  subject  to  decrease. 

Table  E  is  for  the  laboring  classes  whose  earnings  are  subject  to 
much  the  same  law  as  that  of  the  artisan. 


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EXCErTlONS  TO   01" H   RULES.  109 

In  cases  where  ihe  blame  of  an  accident  may  be  laid  upon  the 
second  party  or  where,  through  previous  business  agreement,  an 
employer  or  insurance  company  has  arranged  to  pay  a  fixed  sum  or 
a  pension  in  case  of  accidental  injury,  the  amount  of  the  indem- 
nity should  be  in  accordance  to  a  definite  schedule  based  upon  the 
average  wages  in  the  vocation  to  which  the  individual  may  belong. 
It  should  be  remembered  that  partial  loss  of  vision  not  exceeding 
25  per  cent,  in  vocations  having  higher  visual  demands  and  not 
exceeding  50  per  cent,  in  those  with  lower  demands  does  not  injure 
the  earning  ability  to  any  degree.  Indemnity,  for  actual  disability, 
therefore,  should  be  granted  only  those  whose  eyes  are  damaged  be- 
yond reparation  to  a  greater  extent  than  above  named. 

It  is  only  in  vocations  that  have  visual  requirements  that  a 
close  estimate  of  these  visual  values  may  be  made.  In  those  classes 
of  business  life  whose  followers  are  not  engaged  in  manual  labor, 
whose  business  capacity  relies  more  upon  brains  than  iipon  actual 
handiwork,  our  rules  cannot  always  apply,  for  even  a  lalind  man 
could  work  with  monetary  advantage  in  some  trades  and  business ; 
biit  for  the  laborer,  for  the  artisan  and  for  those  professions  in 
which  the  visual  perceptive  faculties  are  necessary,  our  rules  and 
tables  may  be  deemed  fitting.  By  adjusting  the  age  scale  for  the 
pecuniary  earnings,  to  the  percentage  of  the  actual  damage  as  fig- 
ured by  the  method  of  Magnus,  we  may  arrive  at  an  exact  mathe- 
matical estimation  of  the  economic  damage  to  the  individual  for 
the  loss  of  vision  in  any  given  case. 

It  may  be  well  to  discuss  the  value  of  vision.  This  may  be 
summed  up  in  one  sentence,  "'Sight  is  priceless,  and,  lil'e  lionor,  is 
not  a  marl-etnhle  commodity."  Even  the  mere  perception  of  light  is 
of  inestimable  value  to  a  person  who  is  economically  blind  and  its 
value  to  him  cannot  well  be  calculated.  Does  this  fact  conflict  with 
our  propositions  ?  We  do  not  think  it  can  be  considered,  as  we  are 
not  dealing  with  any  arbitrary  value  that  might  possibly  bo  placed 
upon  the  sense  of  sight,  but  sole!}'  with  the  earning  capacity 
of  the  eyes,  which  has  to  do  with  the  amount  and  quality 
of  remuuerative  work  and  the  duration  of  working  life.  Can  we  a]i])lv 
our  rules  to  the  case  of  non-workers,  for  instance,  to  infants,  chil- 
dren and  those  whose  business  does  not  require  eye  siuht,  or  can  we 
figure  upon  the  ambition  or  possible  prospects  of  advancement  in 
any  other  profession  than  that  in  which  the  person  is  employed? 
It  is  self-evident  that  we  can  not.  For  instance,  one  of  the  children 
in  a  family  may  some  day  become  a  millionaire,  whereas  one  of  his 
brothers  may  ever  remain  a  common  laborer.  There  is  no  means  of 
foretelling  the  future  .  AVe  can  only  figure  with  facts,  and  thus  our 
rules  and  estimations  are  based  upon  the  compensation  of  th':' 
person  before  the  accident,  and  this  is  the  only  proposition  that  can 
be  received.  Indemnification  in  the  case  of  loss  of  sight  from  acci- 
dents in  children,  in  the  majority  of  women,  in  persons  who  are 


110  VALUE   OF   SIGHT. 

working  hut  U'lnporarily  at  some  vocation,  who  ex{)eft  to  enter 
another  at  some  later  period  of  lite,  will  have  to  he  given,  as  here- 
ioJ'ore,  by  arbitrary  decisions  of  the  courts.  Such  reasonings  are 
the  common  rules  of  bnsiness ;  for  instance,  a  man  who  has  no  in- 
come whatever  and  can  offer  no  collateral  would  l)e  refused  a  loan 
of  money  by  any  bank  or  business  corporatii  n.  and  could  not  obtain 
any  money  except  as  an  act  of  charity  or  for  some  extraneous  reason 
foreign  to  the  rules  of  business.  A  ])erson  with  a  small  income, 
for  instance,  earning  $1,000  a  year,  would  be  able  to  borrow  a  cer- 
tain small  amount,  for  instance,  $100,  but  another  ]>erson  earning 
$10,000  a  year  would  be  able  to  borrow  a  vastly  greater  amount 
upon  his  prospects.  Thus  for  business  reasons  we  can  only  con- 
sider actual  Avage  earners  to  come  under  our  rules.  As  accidental 
injuries  involving  compensation  for  damages  happen  in  a  very  large 
majority  of  cases  to  persons  of  this  class,  all  others  may  be  looked 
upon  as  exceptions  and  such  cases  may  he  left  to  be  treated  froiu 
the  philanthropic  standpoint. 

"While  by  this  method  of  reasoning  we  are  enabled  to  exactly  es- 
timate the  amount  of  money  that  a  given  case  may  reasonably  ex- 
pect to  earn  provided  he  remain  in  the  same  business  and  exercise 
ordinar}^  skill  and  diligence  and  hence  accomplish  an  average 
amount  of  work,  it  must  be  admitted  that  such  figures  are  hypothet- 
ical. However,  such  immense  interests  as  those  of  the  modern  in- 
surance companies  and  many  other  sociologic  standards  are  success- 
fully based  upon  the  same  principles  and  we  must  here  be  allowed 
to  use  them.  The  result  to  be  achieved  by  all  our  computations  is 
not  the  exact  amount  that  a  man  will  earn,  but  that  which  he  may 
reasonably  expect  to  receive  for  his  labors. 

§42.     Examples. 

We  will  now  take  up  some  specific  examples  to  illustrate  the  ap- 
plication of  our  methods  for  determining  the  amount  of  economic 
damage  to  the  individual  from  ocular  injuries. 

Example  1.  For  our  first  example  Ave  take  a  case  that  often 
comes  up  in  the  courts  of  law.  An  artisan  whose  business  has  high- 
er visual  demands,  Avho  has  previouly  had  nornuil  vision,  receives 
an  injury  to  one  eye  Avhile  working  at  his  trade,  by  which  the  sight 
of  the  injured  eye  is  wholly  lost,  the  vision  in  the  other  remaining 
normal.  The  question  then  arises.  Avhat  economic  damage  has  this 
man  sustained  ? 

We  have  shown  that  in  the  higher  class  of  trades,  during  the 
first  year  folloAving  the  accident,  a  one-eyed  person  has  lost  30  per 
cent,  of  his  earning  ability  and  afterAvards  the  loss  may  be  reckoned 
as  20  per  cent.  As  a  matter  of  convenience  Ave  Avill  suppose  that 
this  man  is  injured  at  the  30th  year  of  age.  and  that  he  has  been 
■earning  for  the  previous  five  years  $1,000.00  a  year,  Avith  the  expec- 


KXAMI'LES.  Ill 

tation  of  earning  this  sum  annually  until  he  is  50  years  of  age,  when 
for  the  next  15  years  his  average  earnings,  on  account  of  disabil- 
ity, due  to  a^e  and  the  competition  of  younger  workmen,  will  fall 
to  $750.00  a  year  and  his  working  life  is  to  cease  at  G5  years.  His 
total  earnings  for  the  balance  of  his  life  would  then  be  reckoned 
as  follows :  20  years  at  $1,000.00  a  year;  15  years  at  $750.00  a  year ; 
total,  $31,250.00.  For  the  first  rear  after  the  accident  instead  of 
earning  $1,000.00  he  may  expect  a  loss  of  30  per  cent.  ($300.00) 
and  for  the  following  nineteen  ^ears  instead  of  $19,000.00  he  would 
lose  20  per  cent.  ($3,800.00)  and  the  following  fifteen  rears  in- 
stead of  $11,250.00  he  would  lose  20  per  cent.  ($2,250.00)',  making 
a  total  loss  for  the  thirty-fivo  years  of  working  life  of  $6,350.00. 
which  is  his  personal  economic  damage,  an  amount  which  he  might 
reasonably  demand  as  an  indemnity  for  the  loss  of  earning  ability 
due  to  the  accident  if  liability  of  the  emplo3'er  or  djcfendant  could 
be  proven.  This  sum  should  be  used  as  the  scientific  basis  for 
settlement  of  contested  cases :  modified  according  to  American  laAV 
by  a  reduction  being  made  in  favor  of  the  defendant  in  case  of 
extenuating  circumstances  or  contributory  negligence  and  an  addi- 
tion made  thereto  for  actual  expenses  incurred  by  the  plaintiff  dur- 
ing his  illness  and  damages  for  the  pain  and  anguish  suffered  by 
reason  thereof.  These  amounts  must  ahvays  be  empirically  esti- 
mated by  the  courts.* 

ExAiiPLE  2.  If  this  man  were  injured  at  the  age  of  40  the  same 
method  of  calculation  would  give  him  a  prospective  compensation 
of  $21,250.00  for  the  balance  of  his  earning  life,  instead  of  which, 
for  the  first  vear  he  Avould  receive  $700.00,  for  nine  vears  more, 
$7,200.00,  and  for  the  fifteen  years  following  $9,000.00;  making 
a  total  economic  value  of  $10,900.00,  a  resulting  economic  damage 
of  $4,350.00. 

ExA:\rrLE  3.  If  this  man  were  injured  at  the  age  of  50,  instead 
of  his  prospective  compensation  being  $750.00  per  year  for  fifteen 
years,  or  $11,250.00,  for  the  first  year  after  the  accident  he  would 
be  earning  30  per  cent,  less,  or  $525.00,  and  for  the  following  four- 
teen years  20  per  cent,  less,  or  $8,400.00,  making  total  economic 
value^f  $8,925.00  and  total  economic  damage  of  $2,325.00. 

By  the  use  of  different  rates  of  compensation  and  different  years 
other  examples  could  be  readily  given.  The  same  method  of  rea- 
soning applied  to  the  loss  of  one  eye  in  case  of  an  artist  or  other 
professional  man  would  yield  proportional  results.  The  only  dif- 
ference in  the  calculations  would  bo  the  fact  that  such  professions 
usually  become  more  remunerative  as  the  person  grows  older.  In 
the  ease  of  the  common  laborer,  the  only  differences  would  be  the 
lower  rate  of  compensation  and  the  figuring  of  his  economic  loss 

•Seven  thousand  doHarn  has  lieen  recently  awarded  in  Texas  for  the  loss  of  an  eyi-. 
Court  Civil  Appeals  Texas,  I'.iOl,  De  La  Vergne  RefriK'-ratin^i  Mafhine  Co.  vs.  Stahl. 


112  LXA^IIT.KS. 

at  20  per  cent.  I'or  the  first  year  after  the  accident  and  IS  per  cent, 
thercal'ter. 

We  will  now  cro  on  to  the  calcnlations  involved  in  more  complex 
cases  where  the  same  principles  arc  to  be  used  as  those  which  have 
been  invoked  for  simple  cases  : 

Example  4.  AVe  will  take  the  case  of  an  architect  or  draufi:hts- 
man,  in  his  46th  year  of  life,  earning  $3,000.00  a  year,  whose  visual 
acuity  in  one  eye  is  reduced  by  an  accident  to  0.50,  the  other  re- 
maining normal.  His  profession  demands  good  vision  and  he  is  in  a 
measure  handicapped  for  some  of  his  work,  especially  that  of  fine 
draughting.  We  will  proceed  to  work  out  this  case  from  the  be- 
ginning and  will,  therefore,  recapitulate  our  formula: 

X 

In  this  case  the  maximum  0  remains  unchanged  because  this  is 
the  higher  visual  acuity  of  the  sound  eye=l.  V^  p  the  visual  field, 

4 

and  y  M  the  muscular  action  remain  unchanged ;  the  three  factors 
each  representing  the  value  I.  In  this  case  the  unknown  quantity 
is  the  ability  to  compete. 


F 


'^'■p'-yYVM. 


' — - — ~-  being  the  aritlimelical  proportion  of  the  central  visual 

acuity  of  both  eyes.  Ci,the  uninjured  eye  remains  =  1;  Cs  the  in- 
jured eye  should  be  reduced  to  0.50  of  the  scientific  value  0.5,  of 
the  scientific  standard.  Looking  now  on  plate  I.  on  the  absciss  for 
the  scientific  value  0.5,  trace  this  line  upwards  until  we  meet  the 
ecnomic  curve  II.  which  is  for  vocations  having  higher  visual 
demands,  and  from  the  point  Avhere  the  line  cuts  the  curve 
we  go  to  the  left  and  find  there  on  the  ordinate  the  economic  value 
of  the  scientific  estimation  for  the  acuity  of  vision.  This  is  0.58; 
inserting  this  value  into  the  arithmetical  proportion  of  the  acuity 

i.      1    .1  .   ,     C,  +  C,        ,         1    +  0.58     ^  ^n      rri  • 

for  both  eyes,  into         '        we  have  =0.79.     This  we  m- 

X 

sert    into   the    factor       \   ^^^  V  P  V  M    :       we      then      have 


.    f  0.7^ 


2 

4 

9  VYVIa 


EXAMPLES.  1 13 

in    which   V  P    and  \  M    are   each  ^=^1 ;  the    whole    value    is    then 


r 


0.79  X  1  X  1. 


As    this    is    a    slight    injury,    the    ahility    to    compote    is    only 

partly  impaired, so  we  make  tiie  root  exponent  X=10.  Tliis  value 
1(1 

V  0.79X1X1  'wo  can  find  in  phite  II.,  curve  Y.,  where  we  look  on 

tlio  absciss  for  the  value  0.T9,  trace  the  line  from  there  upwards 

until  we  meet  the  curve  Y.,  going  from  there  to  the  left  oa  the 

ordinate  we  find  the  vahie  0.972.     If  we  insert  this  value  into  the 

formula  we  would   find  E=1X1X1X0.972,  which  multiplied  by  100 

gives  the  earning  ability  E  =  97,  2  "b.      This  man  being  injured  at 

his  46th  year,  he  would  expect  to  have  earned  $00,000  during  the 

next  twenty  years.     His  earning  ability  being  reduced  to  97.2  ])er 

cent,  he  would  probably  earn  $58,320.00,  which  subtracted  from  the 

reasonable  expectations  of  his  business,  would  leave  the  sum  of 

$1,680.00,  an  amount  which  he  might  expect  as  the  indemnity  for 

the  loss  of  earning  ability  due  to  the  accident. 

Exa:n[ple  .").  Ir.  the  case  of  a  printer  who  was  originally  weak- 
sighted ;  the  vision  of  one  eye  ni  =  0.05  and  the  other  n;  =  0.55 
(scientific  standard)  ;  eye  1  being  uninjured  (ci=0.05)  while  the 
visual  acuity  of  the  other  has  been  impaired  by  injury  to  c-.=  0.20. 
He  is  in  his  26th  year  and  has  been  earning  $1,000.00  annually  and 
would  reasonably  expect  to  earn  this  sum  for  the  next  25  years, 
after  which  his  earnings  through  disabilities  of  his  age,  slow- 
ness and  consequent  inability  to  compete  would  probably  depreciate 
to  $750.00  a  year,  making  the  balance  of  the  money  that  he  might 
reasonably  expect  to  earn  in  the  course  of  his  life  $36,250.00.  Fig- 
uring out  the  earning  ability  according  to  our  modified  formula  :* 

Cl  „  „_  0.65  r~- 

Ci  =  n        =  0.  /  o  „  „^  =  0.  ( o. 
Hi  0.6o 

c>  0.55 

c,  =  n  —  =:  0.75    ':^  =  0.27, 

n..  O.oo 

the  maximum  ci=Ci  =0.75  while  we  get  for  the  maximum  of  the 
real  acuities  e,„ax.  =  Ci  =  0.65.  The  first  value  should  be  replaced 
professionally  bv  1  according  to  table  B,  p.  42 :  the  second  bv 
0.83 


•These  numbers  are  found  by  referring  to  table  r>,  part  IV  without  calculation, 
coiiiplicatetl  cases  as  these  (Cases  5  and  ti)  wouid  be  rarely  found  ia  practice. 


114  KXAMPLKS. 

To  Ciandcai'iiriiishcs  us  tlie  quniitity  K, '=77. 079,  the  earning 
aliilitv  is  tliereforo: 

c'_.XE'_lX77.079_ 

cmax.  "  0.8333  -•'^•^^'^- 
or  a  permanent  disability  of  7.505  per  cent.  The  amount  that  be- 
fore the  accident  be  niiglit  reasonably  have  expected  to  earn  during 
the  balance  of  his  life  is  $oG,"-50.00,  7,505  per  cent,  of  wliich  would 
give  $2,720.50,  which  should  be  the  highest  amount  allowed  as  in- 
demnity for  the  permanent  loss  of  earning  ability  due  to  the  acci- 
dent subject  to  reduction  for  cause  and  to  increase  as  determined 
in  Example  I. 

Example  (>.  In  the  case  of  a  la])oi-er  who  was  originally  blind 
in  one  eye,  the  other  being  weak-sighted  (nr=0.45),  Avho  at  the  age 
of  40  years  suffered  an  injury  to  the  seeing  eye,  and  there  remains 
only  a  visual  acuity  ofc-2=0.25,  because ci=0  has  to  be  used,  there- 
is  c,„ax.  =  C2=  0.25  (professionally  =  0.444  .  .  .)  and  the  modified 
acuity  of  vision  Ci=0,  the  iiiaximum  of  both  values  will  be: 

c/ =  n -^=  0.50  JJ-t^  =  0.28 
R'i  0.45 

Avhich  correspoiids  professionally  with  the  figures: 

100  +  0.28  —  5       ^^,, 

45  ^^-^^^ 

To  Ciand  Cj belong,  according  to  })late  II..  or  l)y  calculating  the  root 

Ei=  39.582;  the  earning  abilitv  is  thertd'ore: 

^       c„„...E'      0.511  .  .  .   39.582        ,„.„ 
E  =  =  r^  ,  4  ,  =  40.519 

C  ,nax.  0.444 

the  loss  of  the  earning  ability  being  54.481  per  cent.  At  the  age  of 
40  years  he  would  be  earning  $800.00  per  year  and  might  reason- 
ably expect  to  earn  this  amount  for  10  years,  after  M'hich,  owing  to 
physical  infirmities  and  increasing  age,  his  earning  powers  \vould 
probably  be  less,  being  reduced  to  $000.00  per  annum;  he  would, 
therefore,  expect  to  earn,  if  he  had  remained  in  good  physical 
health,  the  sum  of  $17,000.00;  after  the  accident  his  earning  powers 
being  reduced  to  45.519  per  cent.,  he  would  be  justly  entitled  to  an 
indemnity  in  proportion,  which  would  be  54.481  per  cent,  of  $17.- 
000.00=$9,2G1.77,  which  would  be  likewise  subject  to  increase  or 
decrease  according  to  conditions  of  the  accident  as  established  by 
Jaw. 

ExA;MrLE  7.  A  traveling  salesman,  45  years  of  age,  who  re- 
cently consulted  me  had  bi-nasal  hemianopsia  with  a  remaining 
central  acuity  of  0.20  i]i  both  eyes.  He  stated  that  he  had  this  con- 
dition for  a  number  of  years  and  was  enabled  to  do  all  his  work 
satisfactorily  until  recently  when  the  visiuil  acuity  had  failed,  from 
what  he  previously  thought  was  normal,  to  0.20.  He  was  now  able 
to  get  about  and  sell  some  goods,  but  largely  from  memory,  as  he 


EXAMl'LHS.  115 

could  not  read  Ids  biisincs.s  catalogues  and  letters,  and  was  about  to 
give  up  his  business  entirely.  His  income  depended  upon  sales  made 
and  was  about  $2,00U.00  a  year.  Thus  for  the  balance  of  his  work- 
ing life  his  expectations  would  be  for  20  years  at  $3,000.00  a  year, 
amounting  to  $40,000.00.  According  to  his  experience  he  was  able 
to  do  all  his  work  until  the  visual  acuity  failed  and  we  have 
shown  (page  60)  that  nasal  hemianopsia  does  not  necessarily  in- 
cur earning  disability.  Therefore,  we  Avould  figure  his  economic 
damage  from  the  amount  of  the  reduction  of  the  visual  acuity;  the 
scientific  standard,  0.20,  would  have  an  economic  equivalent  of 
0.38.  Ileasoning  from  this  economic  loss  of  acuity  and  inserting 
same  and  working  out  the  formula,  we  find  that  the  value  of  his 
economic  powers  is  about  30  per  cent.,  Avhit-h  lias  a  pecuniary  valu- 
ation of  $600.00  ]ier  annum,  which  agrees  fairly  well  with  his  les- 
sened expectationt^  of  earning  if  his  vision  should  remain  as  it  is, 
l)ut  if  it  furtlier  deteriorates  he  will  be  totally  incapacitated. 

Example  8.  In  the  case  of  an  iron  moulder  -iO  years  of  age 
receiving  a  blow  upon  his  head  which  laid  him  up  from  work  for  a 
year  and  caused  permanent  homonymous  hemianopsia.  From  the 
<^ffects  of  the  accident,  he  being  laid  up  for  a  year,  afterwards  being 
obliged  to  take  a  lower  position  in  the  same  line  of  work,  which 
])aid  him  about  one-third  less,  wo  would  figure  his  theoretic  loss  by 
means  of  table  on  page  61  as  31.i)  \h'v  cent.,  which  agrees  near 
enough  M'ith  the  actual  conditions  of  his  work,  for  he  was  previously 
earning  $4.00  a  day  and  afterwards  was  enabled  to  earn  but  $2.75 
a  day,  the  total  economic  damage  can  1)e  readily  figured  in  this  ca^e 
as  in  the  foregoing. 

Examples  of  such  character  might  be  multiplied  and  cases  cited 
from  the  most  simple  form  to  that  of  the  most  complicated  char- 
acter. The  foregoing  are  surely  sufficient  demonstration  of  the 
fact  that  the  percentage  of  economic  loss  and  its  pecuniary  equiva- 
lent in  any  given  case  of  ocular  injury,  may  be  readily  ascertained. 
The  diagrams  and  tables  offer  an  easy  method  for  this  mathematical 
calculation.  In  but  few  cases  will  it  be  found  necessary  to  figure 
out  the  formula  in  full,  for  reference  to  the  proper  table  in  part  IV. 
will  at  once  give  the  percentage  of  earning  ability.  The  relative 
values  ot  the  visual  acuity,  tlu^  \isnal  Held  and  the  ocular  muscu- 
lature must  certainly  be  estimntcil  liy  a  scientific  examination  of 
tlie  eyes,  preferablv  liy  nii  Dculist  :  tbese  having  been  obtained  the 
other  factors,  the  age  and  business  of  the  workman  and  his  wages 
may  Ix^  introduced  into  the  formula  and  the  probable  pecuniary 
]iersona1  damage  therel)v  r(>adily  calculated.  Competent  practi- 
tionei's  of  law  or  medicine  oi-  insui-ance  officials  mav  by  thcs  > 
methods  determine  with  exactness,  in  a  nuinner  fair  and  just  to  all 
parties,  the  amouni  of  damage  to  the  earning  abilitv  of  their  clients 
which  may  have  occurred  as  a  result  of  accidental  injuries  to  tlio 
eyes,  and  this  should  be  <-(»nsidei-ed  tlie  ]irinci]-yal  factor  in  the  settle- 
ment of  le<ral  claims. 


PART  FOURTH. 


Tables  for  Estimation  of  the  Different  Forms  of  Damage 
to  the  Visual  Earning  Ability. 


Tables  I  to  VI.    Injuries  to  the  Visual  Acuity. 

Tables  VII  to  IX.    Injuries  to  the  Visual  Field  both  Uncomplicated  and 
Complicated  with  Damage  to  the  Visual  Acuity. 

Tables  X  to  XII.     Uncomplicated  and  Complicated  Damages  of  the  Ocular 
Muscles. 

Tablfs  XIII  to  XXII.     Various  Forms  of  Damage  in  Monocularism. 


Earning  Ability  and  its  Impairment.      One  Eye  Normal,  the 
Other  Injured  but  not  Blind. 


TABLE  I. 

Vocations  with  Higher  Visual 
Demands. 

The  full  professional  visual 
acuity  corresponds  with  the  scien- 
tific standard  0.75;  the  ability  to 

in 

compete  is  figured  with  Y  until  the 
\nsual   acuity  falls  to  0.15,  then 

with  ]    or  y. 


TABLE  IL 

Vocations  with  Lower  Visual 
Demands. 

The  full  professional  visual 
acuity  corresponds  with  the  scien- 
tific standard  0.5;  the  ability  to 

10 

compete  as  figured  with  y  until 
the  visual  acuity  falls  below  0.5, 

10  7 

then  with  Y  or  Y- 


Degree  of 

learning 

Impairm't 

Degree  of 

Earning 

Impairm't 

Scientific 

of  Earning 

Scientific 

of  Earning 

Acuity. 

Ability. 

Ability. 

Acuity. 
1—1.50 

Ability. 

Ability. 

1—0.75 

100 

0.0 

100 

0.0 

0.70 

99.5 

0.5 

0.45 

99.4 

0.6 

0.65 

99.1 

0.9 

0.40 

98.8 

1.2 

0.60 

98.6 

1.4 

0.35 

98.1 

1.9 

0.55 

9S.1 

1.9 

0.30 

97.5 

2.5 

0.50 

97.6 

2.4 

0.25 

96.7 

3.3 

0.45 

97.1 

2.9 

0.20 

96.0 

4.0 

0.40 

96.6 

3.4 

0.15 

95.1 

4.9 

0.35 

96.0 

4.0 

0.10 

94.2 

5.8 

0.30 

95.4 

4.6 

0.05 

93.3 

6.7 

0.25 

94.7 

5.3 

If  the  acu- 

0.20 

94.0 

6.0 

ity  falls  be- 

84.4 

15.6 

0.15 

93.8 

6.7 

'low  0.05 

or 

or 

If  the  acu- 

without 

81.6 

18.4 

itv  falls  be- 

84.4 

15.6 

blindness. 

low  0.15 

or 

or 

without 

78.0 

22.0 

blindness. 

*In  the  German  editions  of  Magnus'  work  Dr.  Hugo  Ilohr  has  carried 
out  the  calculations  to  the  thousandths  of  a  per  cent.  The  figures  are  too 
conaplicated  for  practical  use,  and  as  our  calculations  are  dependent  large- 
ly upon  probabilities  which  are  more  or  less  variable,  the  American  editor 
has  only  accepted  the  calculations  to  1-10  per  cent,  as  jirinted  in  the  follow- 
ing tables;  where  there  would  be  a  fractional  remainder  less  than  0.1  per 
cent,  it  has  been  added  to  the  amount  of  the  impairment:  on  account  of 
this  simplification  the  figures  are  slightly  different  than  those  in  the  II 
•German  Edition. 


Earning  Ability  and  its  Impairment,  One  Eye  Bliod,  the 
Other  Weaksighte<L 

TABLE  III. 

Vocations  -with  Higher  Visual  Demands. 

Full  acuity  of  vision  1,  corresponds  with  the  scientific  standard 
0.75,  and  the  ability  to  compete  is  figured  with  V. 


Visual  Acuity  of 

■ 

Impairment 

lieduction  Per- 

the  Weaksighted 

Earninp:  Ability. 

of  the 

niiesible  After 

Eye. 

Earuing  Ability. 

One  Year. 

0.70 

62. 2 

37.8 

29.7 

0.65 

55.5 

44.5 

37.3 

0.60 

48.9 

51.1 

44.7 

0.55 

42.4 

57.6 

52.0 

0.50 

36.1 

63.9 

59.1 

0.45 

30.0 

70.0 

66.1 

0.40 

24.1 

75.9 

72.7 

0.35 

18.4 

81.6 

79.1 

0.30 

13.0 

87.0 

85.2 

0.25 

8.0 

92.0 

90.9 

0.20 

3.5 

96.5 

96.0 

0.15 

0.0 

100.0 

_ 

100.0 

TABL 

.E  IV. 

■^ 

/ocations  with  Low 

er  Visual  Demands 

, 

Full  acuitv  of  vision  1,  corresponds  with  the  scientific  standard 

5 

0.50,  and  the  ability  to  compete  is  figured  with  V. 


Visual  Acuitv  of 

Impairment 

Reduction  Per- 

the Weaksighted 

Earning  Ability. 

of  the 

missible  Aft^r 

Eye. 

63.5 

Earning  Ability. 
36.5 

One  Year. 

0.45 

28.6 

0.40 

54.5 

45.5 

38.7 

0.35 

45.7 

54.3 

48.6 

0.30 

37.1 

62.9 

58.3 

0.25 

28.7 

71.3 

67.6 

0.20 

20.7 

79.3 

76.6 

0.15 

13.0 

87.0 

85.3 

0.10 

5.9 

94.1 

93.3 

0.05 

0.0 

100.0 

100.0 

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-t  „q 

q 

q 

d 

d 

TO 

X 

i-^ 

d 

d 

>n 

-+' 

TO 

-+  C'-* 

Ol 

y-^ 

1 

Ci 

a 

Cft 

05 

c: 

05 

C5 

X       X 

1- 

X       ■' 

r-t 

i  ■;  i:  •a 

X 

—   0) 
03  p 

"3 

^?.n 

+=  r« 

g  1  5 

ENTIFI 
ANDAHl 
FOU 
ISUAL 
CITITY. 

O 

i.-j 

O 

o 

o 

in 

e 

in 

o 

in 

''  "c  '>  ;= 

-c 

o.^ 

S 

3  ='> 

d 

d 

-t 

d 

d 

d 

d 

r^ 

=^' 

q 
d 

+^ 

4J    00 

•o 

0   3^ 

:S  .2  o  o  a 

o 

fa 

eS.S  «■ 

0 

fa 

ill 

TABLE  VII. 

Earning  Ability  and  its  Impairment  in  Disorders  of  the  Visual  Field  with  Nor- 
mal Central  Visual  Acuity. 


VARIETY  (^F  DEFECT. 


fcc  . 

03X3 


f  Partial  defects  in  one  field  ■] 

I  Concentric  contraction   of  the  field  of  | 

1.  {  one  eye  i 
I  Loss  of  one  temporal  half  of  one  eye  | 
t  Loss  of  the  full  field  of  one  eye  J 

(  Small   concentric   contraction  of  both  ) 

2.  j  fields  reaching  to  60°  ( 
(  Loss  of  the  temporal  half  of  both  fields  S 

3.  Hoinonymous   hemianopsia    dextra  veJ 

sinistra,  superior  vel  inferior 

4.  Great    concentric     contraction    of    both 

fields  reaching  30° 

5.  Total     concentric    contraction    of   both 

fields  reaching  to  5  per  cent. 

g  (  Loss  of  the  nasal  halves  of  both  fields    } 
■  )  Loss  of  the  nasal  half  of  one  field  » 


X 

90.4 

K 

80.0 

M 

68.3 

54.6 
0.0 


i— I  o.S 


9.6 

20.0 

3L7 

45.4 

100.0 


1        100.0        0.0 


TABLE  Vila. 

Ability  to  Compete  and  Impairment  of  Visual  Fields  for  Vocations  with  Higher 
and  Lower  Visual  Demands,  Figured  Separately. 


Case. 

RemainiDg 

Fraction 

of  P. 

5 

K  figured  with  \  for 

Higher  demands  (for 
more  serious  injuries) 

7 

K  figured  with  V  for 
Lower   demands  (for 
more  serious  injuries) 

^       .            Impairmeut 
Earning        ^f  the  Earn- 
Abihty.          ing  Ability. 

Earninp; 
Ability. 

Impairment 
of  the  fram- 
ing Ability. 

1 
2 
3 
4 
5 
6 

'A 
'A 
0 

1 

89.6  10.4 
78.4                21.6 
65.9        ,        34.1 

51.7  48.3 
0                  100 

100                  0 

1 

90.1 

79.3 
67.2 
53.3 
0 
100 

9.9 

20.7 
32.8 
46.7 
100 
0 

122 


9 

-a 

> 


B 
Q 

>-  « 

Q 

."S  "3 

^  s 

3  > 

oQ  :§ 


o   .2 


c 


o 


O 

eo 


o 


o 

"5 


o 


CD    A 


■d 


o 
o 


00 


CD 


05 


CO 


CD 


CO 


o 


O 

d 


o 
d 


o 
d 


o 
d 


id 


CO 


o 
d 


CO 


q 
d 


00 


00       o 

,-;    d 


eo 


o 

(M 


CO 
d 


o 

d 


o 

CO 


00        o 

d      d 


q 
d 


o 
d 


CO 


o 
d 


oo 


CO 


o 
d 


CO 


CO 


o 
d 


(M 

CO 


q 
d 


o 

d 


o 

GO 


CO 
CO 


o 
d 


o)     5 
o 


o 


o  c 


.2       o 


O    ISh 


r^  J*       CO 


a; 

-73 


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CJ  (D    fc-i 

3  2^ 

«  §2 

o  O)   o 

o  ^    ' 
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G    '"'  ^ 


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0) 

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J-1 

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O    o 

O^ 

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M  'to 


G 

o  .2 

CO    o 

•!=;  G 

rG      O 

o   c^ 

a 
<v 


G  o  aj 

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G  3^ 

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O  <1> 

M  .G  i-d 

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G    ^^ 

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CC 


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03 


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6 
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0 

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0 

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0 

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H 
1 

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03 
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0 
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c 

0 

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0 

0 

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0  -g 

Gh  g 

0 

2d- 

?  c 

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0    G 
bD  0 

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(~; 

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a: 

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t3 

CI 

a; 
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0 

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0  'f— < 

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of 

S-i 
03 

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c3 

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0 

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0 

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1— 1 

CC 

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c<i 

CO 

TABLE  X. 

EarDing  Ability  and  Impairment  from  Non-Complicated  Disorders  of  the  Exter- 
nal Ocular  Muscles. 


G    -   « 

^    )  >    CD 


KIND  OF  INJURY. 


o  o 

o  t>,.S 


1—0.75 

Paralysis  of  the  muscles  of  only  Resp. 

one  eye 1         1 — O.oO 

Paralysis  of  the  muscles  of  both  1 — 0.75 

eyes;    in  the  working  eye  only  Resp. 

one  muscle  is  paralyzed yf.        1 — 0.50 

Paralysis  of  the  muscles  of  both  I    1 — 0.75 

eyes;  in  the  working  eye   two  Resp. 

muscles  are  paralyzed ;K        1 — 0.50 

Patalysis  of  the  muscles  of  both  I    1 — 0.75 

eyes;  in  the  working  eye  three  Resp. 

muscles  are  paralyzed ^        1 — 0.50 

Paralysis  of  the  muscles  of  Ijoth  1 — 0.75 

eyes;    in  the  working  eye  four  Resp. 

muscles  are  paralyzed 'yi        1 — 0.50 

Paralysis  of  the  muscles  of  both  1 — 0.75 

eyes;    in  the  working  eye   five  Resp. 

muscles  are  paralyzed j^        1 — 0.75 

Paralysis  of  all  the  muscles  used  1 — 0.75 

by   both    or    bv   the    working  Resp. 

eye .". ,  0         1—0.50 


75.4        24.6 


71.8       28.2 


67.5       32.5 


62.3        37.7 


55.8        44.2 


46.1       53.9 


0.0      100.0 


1 
< 


U    :p       _ 


^     "5. 


3    :S 
O     fe 


g 

< 


(4 


IC 


ooqooo 


o 
d 

05  CO  CO  O  CO  05 

Tf  TjH   -.^  T^H  CO  C4 

»o      »o  O  ^3^  CO  t>-  '^ 

'^     d  d  d  Qo  t^  CD 

O       »-i  ,-1 

O       -*  CO  CD  lO  '^  O 

"^     CD  lo  '*'  CO  c<i  d 

to 
CO 

d 

»0  -^  "-^  CO  CD  t-- 

c<i  •.-H  o  cc  CO  CO 

C<)  <M  (M  ■—  —  ^ 

0.40 

00  T}<  c-  OC  CO  CD 

CO  i>^  id  CO  T-I  |>I 

(M  <M  (N  C<I  (M  '-- 

0.45 

CO  TT  lO  -^  O  lO 

id  co'  — <'  ci  CO  ^ 

CO  CO  CO  -M  (M  (M 

0.50 

t^  CD  CO  -^^  GO  ""T 

— i  Ci  t-^  '^'  d  "5 
-*  CO  CO  co-ro  OJ 

0.55 

CO  OS  (M  05  C~-  lO 

GO  id  CO  d  id  d 

'^  -^  ^  CO  CO  <N 

2 

d 

O  CO  (?<  -^^  CO  CO 

id  (N  d  id  d  co' 

lO  lO  TT  -^  -Tt*  CO 

0.65 

i>.  r--  c<i  o  CD  t>- 

-^  00  id  — <  id  t^ 

CD  lO  lO  lO  -^  CO 

O       CD  C<J  CO  t^  t>.  OS 

•^     o6  ic  ■>-<■  ?d'  d  ^ 

O       CD  CD  CD  lO  lO  -* 

i-O 


-f  00  lO  CC'  00  '— 

id  --  r^  (>i  id  CO 

t—  t^  CO  CD  lO  -^ 


a 
a 
o 


OQ 

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c 

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ti 

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cu   G  §  o 

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a;  Ti   ci   02 


^   O   c 
oo   -^ 


ss 


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m 

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o 

»— 1  ^H  1— 1  .-^  1— 1 

o 

lO  ""^  '—  CO  CD  t^ 

C<l 

(N  — '  d  CC  CO  CO 

o 

C^  (M  (M  -H  1-1  i-H 

lO 

OS  -^  CO  to  CO  OS 

O  OS  t^  lO  C<>  CO 

o 

CO  C<l  (M  <N  (>J  T~i 

o 

lO  CO  CO  CO  <M  T-i 

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d 

CO  CO  CO  CO  (M  (M 

i 

to 

CO  OS  (M  OS  t^-  to 

CO 

CO  to  CO  OS  to  OS 

o 

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o 

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t^  ^  „  t^(M  ^ 

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lO  to  to  -^  "^  CO 

to 

CO  O  CO  00  o  to 

"Tfi 

CD  CO  ~  -rf  o:  O 

o 

CD  CO  to  to  ■^  -^ 

>- 

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lO  1— 1  t^  O-l  LO  CO 

3   1 

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^   v.    S   «   tc    ^ 

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(D    G 
E3    » 

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w 

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c 

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a 


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oo 

o 
o 

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o 

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CO  —1 

o 

Ol 

to 

tH  OS 

T-l 

C50 

d 

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o 

00  <N 

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o 

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to 

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d  d 

d 

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o 

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to 

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CD  CO 

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00  <N 

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to  ■^' 

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c 

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^ 

TABLE  Xllla. 


Earning  Ability  and  Impairment  if  the  Injury  of  One  Muscle  has  to  be  Valued 
Correspondingly  Higher,  in  Special  Vocations. 


bb 

a 
"S 

s 

o 

■ 

5 

K  figured  with  >'  (higher  de- 
mands, only  for  more  seri- 

7 

K  figured  with  V' 
mands,    only 

(lower  de- 
for     more 

t-i 

a 

lous  nijunes. 

) 

serious  inj 

uries.) 

1—1 
02 

> 

a 

■<3 

s 

o 
<v 

Earning 
ability. 

Impair- 
ment. 

Earning 

ability. 

Impair- 
ment. 

j 

6 

1 

■ 
69.1 

30.9 

72.6 

! 

27.4 

5 

K 

65.5 

34.5 

68.9 

31.1 

4 

X 

61.2 

38.8 

64.7 

35.3 

3 

5^ 

56.2 

43.8 

59.6 

40.4 

2 

K 

49.7 

50.8 

53.1 

46.9 

1 

1  / 

40.4 

59.6 

43.5 

565 

0 

0 

0 

• 

100 

0 

100 

bX) 


(X  ^ 

I  -"-^ 

<i»  IS 

C  •-; 

O  -2 


X   > 

PQ       o 


2 


<  3 


6     s 


^  c 

<  .2 

C  TS 

<->  c 

W  _ 


o 


1—1 

d 


to 


o  o 
o2 


lO 

o 


o 
d 

op 

id  id 

OS 

0.25 

11.6 

88.4 

0.30 

CO  1-^ 
1-1  GO 

CO 

d 

26.7 
78.3 

o 
d 

34.9 
65.1 

0.45 

43.5 
56.5 

0.50 

52.3 

47.7 

lO 

o 

61.4 
38.6 

o 

CO 

d 

70  8 
29.2 

0.65 

CO  tr- 

-  dc5 

00^- 

o 
I- 

d 

90.0 
10.0 

-d 

1—1  o 


rt   G 
Wh^ 


CU      ^ 


fcC 


<    :3 


?& 


Q    i: 


E    -^ 


< 


w 


s. 

M 

X 

> 

H 

> 

u 
J 

aJ 

OQ 

o 

c 
a: 

•-J 

< 

u 

c 

,S2        'iJ       .S 


O 

lO 


<3 

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o  o 
d2 


0.10 

8.1 
91.9 

d 

^GO 

8 
d- 

28.4 
71.6 

0.25 

lO  lO 

d  d 

CO  CO 

0.30 

oo 

T-;d 

0.35 

05  i-H 
CO  CO 

o    - 
d 

op 

lO 

d 

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CO  1-1 

oo 

2d 


>. 


^ 

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,o 

a 

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a> 

hn 

a 

s 

CS 

&, 

ci 

a 

l-H 

w 

TABLE  XVII. 

Earning  Ability  and  Impairment  in  Disturbances  of  the  Visual  Field  of  an  Orig- 
inally One-Eyed  Person. 


One-eyed  condition  in  a      One  eyed  condition  in  a 

+3 

professional  sense.                scientific  sense. 

Proliepsioual  visual   de-      rrofessional  vifcual    de- 

Variety ok  De-   ^13 

mands,                                    mands. 

FECT     OF    ^  IS-   ^  ^ 

UAL  Field.        S  ^ 

Hig 

1 

her.             Lower.           Higher.      |       Lowt'r. 

i5S 

Visual  Acuity. 

Visual  Acuity. 

1—0.75 

1—0.75 

1—0  50 

1—0.50 

1—0.75 

1-0.75 

1—0.50 

1-0.50 

< 

E'rning 
\bility. 

[mpair- 
ment. 

E'rning 
Ability. 

Impair-  E'rning 
nient.      Ability. 

Impair- 
ment. 

E'rning 
Ability 

Impair- 
ment. 

Loss  of  the  na- 

sal half,             K 

75.5 

24.5 

75.5 

24.5 

73.6 

26.4 

74.6 

25.4 

Small  concen- 

tric contract'n 

% 

67.7 

29.3 

70.7 

29.3 

68.5 

31.5 

69.8 

30.2 

L088  of  tlie  tem-1 

poral  half,         | 
Great  concentric       2^ 

contraction,       ^ 

reaeliing;  30°,    J 

60.4 

39.6 

60.4 

39.6 

57.7 

42.3 

59.2 

40.8 

TABLE  XVIII. 

Earning  Ability  and  Impairment  in  Disturbances  of  the  External  Ocular  Muscles 
of  an  Originally  One-Eyed  Person. 


9 

One-eyed  condition  in  a      One-eyed  condition  in  a 
professional  sense.                scientific  sense. 

VARIETY  OF 

Professional  visual   de- 
mands. 

Professional  visual   de- 
mands. 

MUSCULAR     -  ^ 
DEFECT.         g  ^ 

Higher.             Lower. 

Higher.             Lovrer. 

1  a  eg 

Visual  Acuity. 

Visual  Acuity. 

f.s 

1—0.75 

1—0.75    1—0.50 

1-0.60 

1—0.75 

1—0.75  1  1—0.50    1— 0..50 

E'rning 
Ability. 

Impair-  E'rning 
ment.      Ability. 

Impair- 
ment. 

E'rning 
Ability. 

Impair-J  E'rning  Impair- 
ment,    i  Ability,  ment. 

Loss  of  1  mus- 
cle,              y. 

Loss  of  2  mus- 
cles,              jH 

95.1 
89.4 

4.9 
10.6 

95.1 
89.4 

4.9 
10.6 

94.6 

88.5 

5.4 
11.5 

94.9 
89.0 

5.1 
11.0 

Loss  of  3  mus- 
cles,             y. 

82.6 

17.4    82.6 

17.4 

81.2 

18.8 

! 

82.0  1  18.0 

Loss  of  4  mus- 
cles,               -y;  [  73.9 

Loss  of  5  mus- 
cles,             i  X  1  61.0 

26.1    73.9 
39.0  1  61.0 

26.1 
39.0 

71.9 
58.4 

28.1 
41.6 

73.0    27.0 
59.9  i  40.1 

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BIBLIOGRAPHY. 


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ALPHABETICAL  INDEX. 


INDEX. 


139 


ALPHABETICAL  INDEX. 


A, 


Ability  to  compete,  Definition  of.  46 

■ —  Foi  iiiiila 40 

—  Estimation    of 40 

—  in  nionocularism  . . 71 

—  Acquired 80 

—  Congenital So 

—  Older     valuation     of     in     mo- 

nocularisni    91 

—  Part  depending   upon   individ- 

ual   47 

—  Part  depending  upon  employer  47 

—  A  factor  of  the  earning  ability  20 
Absciss    (see   also  plates   I.    and 

V).  . 42.  52 

•Artisan  classes   37,  107,  110 

Accident  insurance — 

—  German  law   10 

—  Companies  in  America 14 

—  Methods  of  settlement 1.5 

—  Relation  of  physician  to 21 

—  Officials'     duty    to     determine 

amount 21 

Accommodation,  Damage  to... 44,  99 
Accommodation,  convex  lenses  in 

paralysis  of 45 

Adaption 30 

Allport,   Investigations  of  vision 

of  railroad  employees 40 

—  Division  of  railroad  employees 

into  classes 39,  41 

American  Medical  Association. 
Transact.  Section  on  Oph- 
thalmology   11 

Aphakia 94 

Arbitrary  fixation  of  payments 
for  visual  losses  by  Ameri- 
can insurance  companies...  14 

Arithmetical  proportion   IS.  32 

Atrophia  nervii  optici,  Danger  of 

blindness  from    92,  97 

B. 

Baggagemen   3n 

Baggagemasters   39 

Bargemen    37 

Baudry,  Medical-legal   aspects  of 

injuries  to  the  eye 13 

Becker.    Estimation  •  of    working 

ability 28 

Bell,  Expert  testimony    14 


PAGE. 

Builders 37 

Brakemen    39 

Brewers  and  Maltsters 37 

Brickmakers    37 

Bridge  foremen    39 

Bridge  tenders 39 

Binocular   economic   vision,    For- 
mula  for    33 

Blindness.  Economic  meaning  of.  ;j3 

—  Scientific  meaning  of 33 

C. 

Cerebral   vision 30 

Chemical  workers   37 

Cliimney  sweeps 3y 

Classes  of  railroad  employees..  .39,  41 

Color  sense 24 

Color  blindness 101 

Competition,  difficulty  of  one  eyed 

men '  .  .  87 

Conjunctiva,   injuries  of 96 

— •  Inflammation  of   100 

Conductors,  railroad 41 

Cornea,    staphyloma  of 96 

—  Inflammation   of    96 

—  Opacities  of 96 

—  Injuries  of 96 

Curves.  Geometric,  for  rendering 

the  calculations  and  simpli- 
fying the   f ormulcTe .  .  .  .  42,   52,   55 

—  Showing  scientific  and  the  two 

grades    of    economic    visual 

acuity    (also  plate  I)    42 

—  For  estimation  of  the  factors 

of     economic     vision      (also 

plate  V) 52 

Cyclops,     from    Groenouw's    for- 
mula  20,  29 

Capacity   for   earning   a    living.  .  26 
Congenital     defects.     Adjustment 

in ■ 31 

Convex  lenses  in  paralysis  of  ac- 
commodation  .  .• 45 

Cataract    100 

Chorioiditis 101 

Constitutional   diseases    101 


D. 


Danger  of  blindness  of  one-eyed 

persons    97 


140 


INDEX. 


Damages,  ]Measure  of 14 

—  Definition  of    14 

—  Relation  of  physician  to 17 

—  Relation  of  insurance  officials 

to 17 

—  Nominal    .' 14 

—  Substantial,  conipensatorv    ...  14 

—  Exemplary,  punitive,  vindictive  14 
Damage    to    visual    acuity     (see 

tables,    part    IV. ;    see    also 

visual  acuity    30 

—  to    visual    field     (tables,    part 

IV.)    30,  58,  Gl,  03 

- — to  ocular  muscles  (tables,  part 

IV.) 101.  22.  30,  31.  44,  65 

—  to  economic  vision,  etc 30 

—  to  earning  abilitj^ 24 

—  to  working  ability ....'....;..  28 

Day  laborers    38 

Deformitv    resulting    from    acci- 
dent.      4S 

Despatchers 39 

Diseases,  local,  impairing  earning 

power 100 

Dutv  of  phvsieian 17 

Diplopia  .  ." 101 


Earning  ability.  Definition  of .  .  .      26 

—  Formula   for    28 

—  Factors  of   26 

—  According  to  German  law ....      26 

—  In  normal  health 28 

■ —  How  determined 26 

—  Foersters  false  estimation... 

—  Wagner's  right  estimation.  .  .  . 

—  Hansen's  empirical  estimation  105 

—  Relations  of  visual  acuity  to.     32 

—  Relations  of  visual  acuity  to. 

Avhen  only  one  eye  is  injured 
(see  tables,  part  IV.) 

—  Relations  of  visual  acuity  to. 

when  one  is  damaged  and 
'  other  blind  (see  tables,  part 

IV.)   

Earning  ability 11 

—  in  loss  of  central  visual  acuity 

of  both   eyes 33 

—  in  loss  of  central  visual  acuity 

of  one  eye 33 

—  in  gradually  increasing  blind- 

ness.   .  .  .' 80 

—  in   sudden  blindness    89 

—  in  damage  to  visual  field 58 

—  in  Aphakia    04 

—  in  damage  to  muscles 65 


P.\(iE. 

Economic    limitations    of    visual 

acuity   33 

—  Improper    estimate     of     Groe- 

noiiw    20,  22 

Economic    limitations    of    visual 

lield   43 

Economic     standard     of     visual 

acuity   43 

Elevator   employes    37 

Engineers   39,  40 

Engineering,  Profession  of 36 

Engine  dispatchers   36 

Estimation      of      distances      and 

shapes  of  objects    51 

Expert  evidence  13 

Extrinsic  ocular   muscles 65 

—  Paralysis  of 66 

F. 

Farmers     38 

Fine  mechanics    37 

Firemen 37,  40 

Flagmen    4t) 

Foerster,  Duty  of  physician 21 

Food  article  manufacturers 40 

Foreign  bodies  in  eye 102 

Fuchs    '. 94 

Fundamental  principles  for  esti- 
mation  of   effects  of  ocular 

injuries  24 

Freightmen,  foremen,  masters...  40 


G. 


Garment  makers   37 

Gas  and  water  works  employees.  37 

Gatenien    40 

German  accident  insurance  law. 10,  fO 

— -  Workmen  and  hospitals 16 

German    imperial     insvu'ance   of- 
fice    35,  91 

Glass-blowers   37 

Golebiewski.  Loss  of  one  eye.  ...  91 
—  Commentation  on  accident  in- 
surance law 91 

Greenleaf,   Evidence 13 

Groenouw,    Adjustment    in    con- 
genital   defects    31 

Groenouw.   Formula  of 19 

its  intention   19 

— -  —  has  no  general  application.  20 

is   mathematicallv   insolua- 

ble    ■ 21 

in  monocularism   21 

nii.xes  physiologic  with  ana- 
tomic data    24 


INDEX. 


141 


PAGE. 

—  Xiiie-oyed  monster 21 

—  Cyclops   21 

—  One-eyed  person  hypothetical- 

ly  earns  nothing 20 

Guards 39 

Guillery,    Accidents    in    one-eyed 

persons 86 


H. 


Haab.     Commoner     affections     of 
the  visual  lield 

—  Normal  limits  of  visual  field..  43 

Hansen's  estimates 105 

Heddaeiis,  Formula  of   22 

Hemianopsia    59,  ()1,  63,  101 

—  Double  sided   59 

■ — •  Iraiimatic    59 

Hyperopia    conflicts    with    R.    R. 

service 40 


Indemnity 11 

—  Relation  of  phvsician  to 17 

—  To  the  one-eyed 14,  86,  90 

—  Reduction  one  year  after  acci- 

dent           90 

—  Reduction   of   rates    in   recent 

years   ?0 

Insurance,   (see  accident) 

Intrinsic  ocular  musculature.  .  .44,  99 

Iron  and  steel  workers 37 

Iron  splinters,  Injuries  from.  ...      i  8 

Injury  of  earning  ability 11,  CO 

Iritis    100 


J. 


Jaeger's  types plate  II  and  42 

Jatzow,  Indemnity  to  the  one- 
eyed  ! 92 

Josten,   Economic   Itmitations   of 

central  visual  acuity   34 

—  In  military  service   36 


K. 


Ivaufmann.  Eye  injuries 

Knies.  Loss  of  reading  power  in 

right  hemianopsia    50 


Law.  German  accident   (See  acci- 
dent)   16 

Leather  workers    37 

Left  eye  and  monocularism    ....  92 
Legal     status     of     physician     in 

America    13 

Lens,  Injuries  of 94 

Lewis,    Expert  testimony    14 

Light  sense 30 

Linen  industry    37 

Locomotive  employees    39 

Loss  of  binocular  vision 32 

Lids.  Injuries  of 98 

—  Inflammation  of    100 

Laboring  classes   37 


M. 


Magnus.  Numerous  references... 

Machinists  and  metal  workers..  37 

Marine  employees    37 

Medico-legal   experts    (see  expert 

testimony) 13 

Medical  officers  of  comiianies. ...  13 
ililitary    standard    of    vision    in 

America    36 

—  Germany     36 

]\[edicine.  Profession  of 57 

]\[ill   employees    37 

Mine  workers   38 

-Monocular   economic   vision,    for- 
mula   for    33 

Monocular    blindness.    Danger    of 

total  blindness  in 92 

—  Ability  to  compete  in 79,  87 

—  Definition   of   scientific 70 

— -Definition  of  economic 70 

— -  Complaints  in   93 

—  Acquired 85 

—  Congenital    86 

— -  Central  visual  acuity  in 85 

—  Earning  abilitv  in  acquired..  88 

—  Visual  field  in* 85 

—  ilusculature  in 86 

—  Sudden  blinding  of  one  eye..  88 

—  Slowly  increasing  blindness  cf 

one  eye   91 

—  Estimation    of    distances    and 

shapfs  in    91 

Moses.  Indemnity  to  the  one-eyed  92 

—  Loss  of  sight  in  workingmen. 
Mooren,  Muscular  powers  of  one 

eye 86 

—  Indemnity     in     acquired     mo- 

nocularism    91 

—  Opinion  on  the  accident  law.  .  16 


142 


IXDEX. 


•  I>A(iE. 

—  Loss  of  binocular  vision    ....    lOi 
Muscles    of    the    eyes,    ^Muscula- 
ture  ." .  . 33,  4 1 

—  Intrinsic;    44,  !.0 

—  Extrinsic  in  the  fornuila 44 

—  Economic  relations  of 44 

—  Economic  impoitanoe  of  dam- 

age to   44 

—  Paralysis    of  (tables    in    part 

IV.)     102,  Go 

—  Damage    to    complicated    with 

damage     to  visual       acuity 
(tables   in   part    IV.) 

—  Damage    to   complicated    with 

damage      to       visual      field 
(tables  in  part  IV.) 

—  Damage    to    in    acquired    nio- 

nocularism    So 

Musical  instrument  makers 37 


X. 


Xieden,  Xystagmus  of  miners...      44 

—  Sight  of  the  one-eyed 8U 

Xine-eyed     monster     from     Groe- 

nouw's   formula    21 

Xoyes  &  Oliver 

0. 

Ocular  muscles,    (see  muscles   of 

the  eyes) 

.  Ocular   injuries.    Relation   of,    to 

earning  ability    30 

Ocular  earning  aLilitv.  Definition 

of   '. CO 

One-eyedness,  (see  monocul  ir 
blindness) 

Ottinger,  Statistics  of  eye  acci- 
dents  ' ' 91 

Ordinate  (see  plates  1.  and  V.)  .42,  52 

One-eyed   person  sees  nothing  by 

Groenoinv  formula    21 


P 


Professional  and  business  clauses   130 

Pecuniary  loss   104 

Paper  workers   37 

Paper   makers    37 

Paraly.sis     of     extrinsic      ocular 

muscles OG 

—  intrinsic   ocular   muscles    (ac- 
commodation)     44,  no 

Pension  Bureau.  United  States..      IG 
Pensions,  rente,  indemnity  for  ac- 
cidents   .  .' *.  .  .14,    IG,   01 

Peripheric  vision  (see  visual  field) 


i'.v(;e. 

Pliysician.    Relation    to    accident 

insurance — indemnity    ......      21 

—  Duty   to  deteimiiiie  amciunt  of 

damage  to  earning  ability..      21 

—  Comes    under   class   I.,    higher 

visual  demands 37 

Porters    38 

Pottery  makers   37 

Precious   metal    workers    37 

Professions,  higher,  require  higli- 

er  visual  demands    37 

Printers     37 

Pupils    37 

Q. 

Quanymen 37 

Quarles  (see  dedication  and 
preface) 

R. 

Railway  employees   37 

Railroads,  German  ministry  of. 29,  41 

Railway  relief  associations 40 

Rectus  muscles,  relative  economic 

importance  of 45,  32 

Road  foremen,  masters   39 

Rolling  mill  workers 37 

—  for  Visual  field 38 

—  for  muscle   38 

Root  value  for  ability  to  compete     30 
Relation  of  age  to  earning  abil- 
ity  .3G,    104 

Retina,    Detachment   of 101 

Refraction,  Errors  of   102 

S. 

Schaflfner   

Schloemilcli    

Schmidt -Kimpler,        Hemianopsia 

dujilex  traumatica    59 

Sclunoeckel.    Division    of    R.    R. 

employees  into   classes    ....      39 
Sehroeter,-   Zones    of    the    visual 

field 43 

—  Economic  valuation  of  limita- 

tions of  tlie  visual  field.  ...      59 

—  Economic  valuation  in  hemia- 

nopsia ; 59 

Scientitic  standard  of  visual 
acuity  (transformed  to  eco- 
nomic   terms,    plate    I.    and 

table) 42 

Signal    men     39 

Silex,  Division  of  R.  R.  employ- 
ees into  classes 39 

— -Limit  of  vision  in  R.R.  s.rvice     39 


INDEX. 


143 


PAGE. 

Sinkler.  Rules  of  medical  evidence  13 

Silk  industry   37 

Snellen  types   (plate  III.) 43 

Soldiers  and  sailors   37 

Street  car   (horse  car)   employees  38 

Street   car    (motor)    employees..  37 

Stephen    13 

Station  employees   39 

Station    baggagemen    39 

Station  agents   37 

Statistics  of  one-eyed  workmen .  .23,  90 

Stephen,  Evidence   13 

Sugar  factory  employees 38 

Switchmen 39 

Switchtenders  39 

Symblepharon 96 

Sympathetic    ophthalmitis.    Dan- 
ger of   97 

Sufficient  visual  acuity 39 

Students ^-. 37 


Tabulated  values   (part  IV.)  .... 

Taylor,  Evidence 13 

—  Law  in  relation  to  the  physi- 
cian     13 

Teamsters   38 

Telegraph  operators   37 

Textile  industry    37 

Thomson,   Relative  visual   acuity 
and    color    blindness,    detec- 
tion of   39 

Tobacco  workers   38 

Track  foremen   39 

Three  hypothetical  eyes  from  Ze- 

hender's  formula   19 

Theolog}",  Profession  of 37 

Ti'ain  baggagemen    39 


Vision.  Visual  act  factor  of 32 

—  Physiologic    32 

—  Binocular 33 

—  -  Economic    30 

—  Monocular    33 

Visual  Acuity.  Gradual  loss  of..     27 
Visual  Demands,  Table  for  voca- 
tions with  higher  (part  IV.) 
■ 37,  42 

—  Table  for  vocations  with  lower 

(part  IV.)    37,  42 

Vitreous    opacities    102 

Visual  Acuity — 

—  Definition  of   30 


PAGE. 

—  Scientific  meaning  of 34 

—  Economic  meaning  of 34 

—  Transposition  of  scientific  into 

economic  terms,  plate  I.  and 
table  B 42 

—  Loss  of   

—  Damage  or  injury  to  (tables  I.- 

II..  part  IV.)'. . 

—  Damage  of,  in  connection  with 

defects  of  visual  field  (tables 
VII.-IX.) 66 

—  Damage  or  in  connection  with 

defects  of  muscles 66 

—  In  monocular  blindness 73 

—  Modified   76 

—  Loss  of  in  both  eyes 30 

—  Economic  limit  of 33 

—  Sufficient  limit  of 35 

\'isual  Field,  Binocular   43 

—  ^Monocular    72 

—  Economic  limits   of 43 

—  Economic  valuation  of  damage 

to   binocular    43 

—  Economic  valuation  of  damage 

to  monocular 72 

—  Slight    limitation     (see    plate 

IV.)    

—  ■Great    limitation     (see    plate 

IV.) 

—  Total  loss  of  peripheric  vision  58 

—  Limitation  in  one  eye 58 

—  Partial  defects   in  one   field..  58 

—  Partial  defects  in  both  fields.  58 
— -  Zones    (plate   IV.)     58 

—  Relative   importance   of.  .... .  58 

—  Concentric  contraction    58 

—  Disorders  of.  Complicated....  62 

—  Damage   or  injury  to    (tables, 

part  IV.)    '. 

Von   Woedtke,    German    accident 

insurance  law   16 


W. 

Wagner.  Duty  of  physicians....  21 

Wagon  masters    37 

Walther,    Examination   of   work- 

ingmen's  eyes    74 

Warehousemen,  keepers   38 

W'atchmen     38 

W^eak  sight.  Acquired  in  youth . .  34 

W^eakness  of  vision    44 

—  Congenital    34 

—  Cleaning     of,     from     economic 

standpoint    74 

Williams.  Division  of  R.  R.  Em- 
ployees into  elapses   40 


144 


INDEX. 


PAGE. 

Wipers    39 

Wisconsin  Eeports    13 

Woodworkers  and  carpenters....  37 

Working  ability,  Definition  of . .  .  28 
—  not  synonymous  with  earning 

ability    28 

Wiirdemann,  Numerous  references 


Yardmen 37 


PAGE. 

Z. 

Zehender.  Formula  of 18 

• —  Formula,   Basis  of  his 18 

—  ^Mathematical  value  of   18 

—  The  formula  now  only  of  his- 

toric  importance    19 

—  Examinations    of   workmen ...  75 

—  Three  hypothetical  eyes   19 

—  Lowest     standard     of     visual 

acuity 35 

—  Loss  of  one  eye 92 

—  Danger   of   total   blindness   in 

loss  of  one  eye  92 


PLATES  II  AND  IE. 


Near  and  Distance  Test  Types. 


PLATE  11. 


JAEGER'S  TYPES  WITH  DISTANCES  AT  WHICH  THEY  MAY  BE  NORMALLY 

SEEN  AS  RENDERED  BY  THE  SCIENTIFIC  AND 

ECONOMIC  STANDARDS. 

FOR  NEAR  TEST  OF  THE  VISUAL  ACUITY. 


Economic  Standard  for  Lower  Scientific  Economic  Standard  for  Higher 

Visual  Demands.  Standard.  Visual  Demands. 

0.3  0.6  0,45 

Of  the  seventy=one  conventions  held  here  during  the  present  year,  thirty=two  were 
of  national  associations,  and  thirty^nine  state.  Since  the  annual  meeting  of  a  year  ago 
thirty^nine  national  conventions  have  been  secured  for  Milwaukee  through  the  agency 
of  the  Citizens'  Business  League,  three  of  which  were  for  the  present  year  and  have  al= 
ready  been  held  here,  namely:  American  Society  of  Mechanical  Engineers,  United  States 

0.4  0.8  0.6 

Weather  Bureau  Officials,  and  the  American  Banl<ers'  Association. 
For  next  year  the  list  includes  twenty=eight  national  and  thirty=four 
state  conventions,  and  for  the  year  following,  we  have  already  booked 
eight  national  and  ten  state  conventions.     In  addition  to  those  already 

0.5  1-0  0,75 

secured,  we  are  working  with  a  number  of  im= 
portant  associations  which  we  still  hope  to  se= 
cure  for  Milwaukee  next  year.  Every  time  we 
go  after  a  convention,  if  we  do  not  win  out,  we 

0.75  1-5  1,2 

enter  a  strong  wedge  to  bring  it  here  an= 
other  year.  Among  those  we  are  hoping 
to  secure,  selections  having  been  referred 
to  executive  committees,  are  the  Traveling 

\J^  3.0  2.4 

Freight  Ag^ents'  Associa= 
tion  of  the  United  States, 
the  National  Lumber  Com 


PLATE  III. 


SNELLEN'S  TYPES  WITH   DISTANCES  AT  WHICH  THEY  MAY  NORMALLY 

BE  SEEN  AS  RENDERED  BY  THE  SCIENTIFIC  AND 

ECONOMIC  STANDARDS. 

FOR  DISTANT  TEST  OF  THE  VISUAL  ACUITY. 


Economic  Standard  for 

Xower  Visual  Demands, 

12  meters. 


Scientific  Standard, 
24  meters. 


Economic  Standard  for 

Higher  Visual  Demands, 

18  meters. 


'St' 


3  meters. 


-tVi  meters. 


PLATE  IV. 


The  Visual  Field. 


PLATE  IV. 


normal  Binocular  Uliual  Tltld. 

The  yellow  area  is  tli.-  jiortioii  lomraf.ii  to  both  eyes;  the  red  belo 
to  the  left  and  the  blue  to  the  luoiiociilar  field  of  the  right  eye 
The  heavy  black  circles  divide  the  fields  into  three  zoues  of  ec 
economic  importance.    Chapter  VI,  §  13. 


Co»  of  th(  temporal  nalcts  or  Botlt  Ulsual  Titlds 

Valuation  of  the  Remainder  is  -a  nf  the  Normal. 
Chapter  IX,  «  Ifl. 


Coss  of  the  nasal  fnAm  of  Both  Ulsital  TKIds. 

A'ahiatiou  of  the  Kemainder  is  I. 
Chapter  IX,  Uil. 


Coss  of  lilt  nasal  fialf  of  tht  Ulsual  f  itld  oi  ihe  Dii  eyt. 

Valuation  of  the  Remainder  is  1 . 
Chapter  IX,  S  l!l. 


Coss  of  lite  tomporal  Half  of  ihe  Ulsual  TKid  of  iitt  Rlflbi  Eyt. 

Valuation  of  the  Kemainder  is  %  . 
Chapter  IX,  S 19. 


Normal  and  Damaged  Visual  Fields  with  E,conomic  Valuation. 


.Mrr. 


PLATE  V. 


Curves  for  Valuation  of  the  Visual  Field,  of  the  Muscular  Action 
and  of  the  Ability  to  Compete. 


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Form  L9-Series  4939 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


A     000  414  492     9 


